- April 12 – The Townshend Acts were repealed by Britain's Parliament by the efforts of Prime Minister Frederick North, with the exception of the increased duties on imported tea. The American colonists, in turn, stopped their embargo on British imports.
- April 18 (April 19 by Cook's log) 18:00 – First voyage of James Cook: English explorer Captain James Cook and his crew become the first recorded Europeans to encounter the eastern coastline of the Australian continent.
- April 20 – Battle of Aspindza: Georgian king Erekle II defeats the Ottoman forces, despite being abandoned by an ally, Russian General Totleben.
- April 29 – First voyage of James Cook: Captain Cook drops anchor on HMS Endeavour in a wide bay, about 16 km (10 mi) south of the present city of Sydney, Australia. Because the young botanist on board the ship, Joseph Banks, discovers 30,000 specimens of plant life in the area, 1,600 of them unknown to European science, Cook names the place Botany Bay on May 7.
- May 7 – Fourteen-year-old Marie Antoinette arrives at the French court.
- May 16 – Marie Antoinette marries Louis-Auguste (who later becomes King Louis XVI of France).
- May 20 – A stampede, at a celebration of the newly wedded Marie Antoinette and Louis-Auguste in Paris, kills more than a hundred people.
- June 3 –
- June 9 – Falklands Crisis (1770): Some 1,600 Spanish marines, sent by the Spanish governor of Buenos Aires in five frigates, seize Port Egmont in the Falkland Islands. The small British force present promptly surrenders.
- June 11 – First voyage of James Cook: HMS Endeavour grounds on the Great Barrier Reef.
- January 5 – The Great Kalmyk (Torghut) Migration is led by Ubashi Khan, from the east bank of the Lower Volga River back to the homeland of Dzungaria, at this time under Qing Dynasty rule.
- January 9 – Emperor Go-Momozono accedes to the throne of Japan, following his aunt's abdication.
- February 12 – Upon the death of Adolf Frederick, he is succeeded as King of Sweden by his son Gustav III. At the time, however, Gustav is unaware of this, since he is abroad in Paris. The news of his father's death reaches him about a month later.
- March – War of the Regulation: North Carolina Governor William Tryon raises a militia, to put down the long-running uprising of backcountry militias against North Carolina's colonial government.
- March 12 – The North Carolina General Assembly establishes Wake County (named for Margaret Wake, the wife of North Carolina Royal Governor William Tryon) from portions of Cumberland, Johnston and Orange counties. Bloomsbury (later known as Wake Courthouse) is made the informal county seat.
- March 15 – The Smeatonian Society of Civil Engineers first meets in London, the world's oldest engineering society.
- April 4 – The first quarantines are started in Moscow and Saint Petersburg to fight the bubonic plague. Over the next 12 months, more than 52,000 people die from the plague in Moscow alone.
- May 11 – War of the Regulation: North Carolina Governor William Tryon marches his military out of Hillsborough, to come to the aid of General Hugh Waddell's beleaguered forces. Tryon's army stops at Alamance Creek, 5 miles (8.0 km) away from the Regulator army.
- May 16 – War of the Regulation – Battle of Alamance: Regulators reject an appeal by Governor Tryon to peacefully disperse. Governor Tryon's forces crush the rebellion, causing many Regulators to move to frontier areas outside of North Carolina.
- May 23 – Battle of Lanckorona: A force of 4,000 Russians under Alexander Suvorov defeat a Polish formation of 1,300 men.
- May – Three battles of Sarbakusa: An alliance of three of the most powerful aristocrats of Ethiopia (
Goshu of Amhara, Wand Bewossen, and
Fasil of Damot) defeats Ras Mikael Sehul and Emperor Tekle Haymanot I, taking control of Ethiopia.
- June 11 — The Society of Gentlemen Supporters of the Bill of Rights meets in the London Tavern and changes its platform from to a comprehensive program for British parliamentary reform in advance of the next election.
- July 12 – The first voyage of James Cook around the world ends as HMS Endeavour returns to England after almost three years.
- July 13 – Russo-Turkish War (1768–74): Russian forces occupy the Crimea, under Prince Vasily Dolgorukov.
- July 17 – Bloody Falls massacre: Chipewyan chief Matonabbee, traveling as the guide to Samuel Hearne on his Arctic overland journey, massacres a group of unsuspecting Inuit.
- August 8 – The first recorded town cricket match is played, at Horsham, England.
- September 8 – In California, Fathers Pedro Cambon and Angel Somera found Mission San Gabriel Arcángel, in what is now San Gabriel, California.
- September 15–17 – The Moscow plague riot results from an outbreak of bubonic plague, which kills 57,000.
- October 9 – The Dutch merchant ship Vrouw Maria sinks off the coast of Finland; Captain Raymund Lourens and his crew escape unharmed.
- October 17 – The opera Ascanio in Alba by Wolfgang Mozart, age 15, premieres in Milan.
- November 16 – During the night the River Tyne, England, floods, destroying many bridges and killing several people; the replacement main bridge at Newcastle upon Tyne will not be completed until 1781.
- December 3 – The cause of action in Sommersett's Case, which eventually leads to the end of slavery in Great Britain, begins when escaped slave James Sommersett is found imprisoned on the ship Ann and Mary.
- December 31 – Men, women and children of the Choctaw and Chickasaw tribes begin a 23-day encampment at Mobile, part of the British colony of West Florida, at the invitation of British Southern Indian superintendent John Stuart, as their leaders negotiate a treaty.
- The territory of Baden-Baden is inherited by Charles Frederick, Margrave of Baden-Durlach, reunifying the territories of Baden.
- The trade monopoly with Iceland is transferred to the Danish crown.
- The North Carolina General Assembly passes an act establishing the town of Martinsborough, named for Royal Governor Josiah Martin, on the land of Richard Evans, which will serve as the seat of Pitt County.
- Construction of the Putuo Zongcheng Temple complex in Chengde, China is completed during the reign of the Qianlong Emperor.
- Limoges porcelain manufacture is established in France.
- Slovene literature: István Küzmics, the Hungarian Slovene writer and evangelical pastor, publishes (in Halle) the Nouvi Zákon, a translation of the New Testament into the Prekmurje Slovene language, with discrete South Slavic artwork.
- April 8 – Massachusetts legislator Samuel Adams persuades his colleagues to approve his plan for creating a Committee of Correspondence to begin a dialogue with the other American colonies concerning mutual problems with the United Kingdom.  
- April 13 – Warren Hastings begins his service for the British East India Company as Governor of Bengal, arriving at the company's headquarters at Fort William, outside of Calcutta, and including what are now parts of northeast India and Bangladesh.  Hastings serves for two years, then later becomes Governor-General of India.
- May 8 – The Watauga Association Compact is signed in what is now East Tennessee by a group of white settlers led by William Bean, creating the first non-colonial government body in British North America. 
- June 9 – Gaspee Affair: In an act of defiance against the British Navigation Acts, American patriots, led by Abraham Whipple, attack and burn the British customs schooner HMS Gaspee off of Rhode Island.
- June 10 – The Credit crisis of 1772 is triggered when, following the flight of their partner Alexander Fordyce to France, the London banking house of Neal, James, Fordyce and Down (which has been speculating in East India Company stock) suspends payment. The resultant panic causes other banks, particularly in Scotland, to fail, extends to Amsterdam and the Thirteen Colonies of British North America, and threatens the East India Company with bankruptcy.
- June 22 – Somersett's Case: Lord Mansfield, the Lord Chief Justice of England and Wales, delivers the decision that leads to the end of slavery in England.
- January 1 – The hymn that becomes known as Amazing Grace, at this time titled "1 Chronicles 17:16–17", is first used to accompany a sermon led by curate John Newton in the town of Olney, Buckinghamshire, England.
- January 12 – The first museum in the American colonies is established in Charleston, South Carolina; in 1915, it is formally incorporated as the Charleston Museum.
- January 17 – Second voyage of James Cook: Captain Cook in HMS Resolution (1771) becomes the first European explorer to cross the Antarctic Circle.
- January 18 – The first opera performance in the Swedish language, Thetis and Phelée, performed by Carl Stenborg and Elisabeth Olin in Bollhuset in Stockholm, Sweden, marks the establishment of the Royal Swedish Opera.
- February 8 – The Grand Council of Poland meets in Warsaw, summoned by a circular letter from King Stanisław August Poniatowski to respond to the Kingdom's threatened partition between three foreign powers.
- February 27 – The construction of Christ Church (Alexandria, Virginia), known for being the house of worship for George Washington and the visiting site for subsequent U.S. presidents, is completed.
- March 9–19 – Second voyage of James Cook: Tobias Furneaux in HMS Adventure (1771) explores the coast of Van Diemen's Land.
- March 15 – The popular (and enduring) comedy She Stoops to Conquer, by Irish playwright Oliver Goldsmith, is performed for the first time, premiering at London's Covent Garden Theatre.
- October 10
- October 12 – America's first insane asylum opens, for Persons of Insane and Disordered Minds, in Williamsburg, Virginia.
- October 13 – French astronomer Charles Messier discovers the Whirlpool Galaxy, an interacting, grand design spiral galaxy located at a distance of approximately 23 million light-years, in the constellation Canes Venatici.
- October 14 – The Komisja Edukacji Narodowej (Polish for Commission for the Education of the People), formed in the Polish–Lithuanian Commonwealth, is considered to be the world's first ministry of education.
- November 10 – Four ships— the Dartmouth, the Eleanor, the Beaver and the William— depart Britain for America, carrying the first Indian tea to be subject to the newly enacted taxes. The William is lost in a storm; the Dartmouth is the first ship to reach Boston, docking on November 28.
- December 16 – Boston Tea Party: A group of American colonists, dressed as Mohawk Indians, steal aboard ships of the East India Company and dump their cargo of tea into Boston Harbor, in protest against British tax policies.
- Russo-Turkish War, 1768-1774: Russian forces fail to take Silistria.
- Emelian Pugachev starts Pugachev's Rebellion in Russia, attacking and occupying Samara.
- John Harrison's wins the Longitude prize, for his invention of the marine chronometer.
- Hilaire Rouelle discovers urea.
- Istanbul Technical University is established (under the name of Royal School of Naval Engineering) as the world's first comprehensive institution of higher learning dedicated to engineering education.
- In China, written work begins on the Siku Quanshu, the largest literary compilation of books in China's history (surpassing the Yongle Encyclopedia of the 15th Century). Upon completion in 1782, the books are bound in 36,381 volumes (册) with more than 79,000 chapters (卷), comprising about 2.3 million pages, and approximately 800 million Chinese characters.
- Scottish judge James Burnett, Lord Monboddo, begins publication of Of the Origin and Progress of Language, a contribution to evolutionary ideas of the Enlightenment.
- Friedrich Gottlieb Klopstock publishes the last five cantos of his epic poem Der Messias in Hamburg.
- January 21 – Mustafa III, Sultan of the Ottoman Empire, dies and is succeeded by his brother Abdul Hamid I.
- January 27 – An angry crowd in Boston, Massachusetts seizes, tars and feathers British customs collector and Loyalist John Malcolm, for striking a boy and a shoemaker, George Hewes, with his cane.
- February 3 – The Privy Council of Great Britain, as advisors to King George III, votes for the King's abolition of free land grants of North American lands. Henceforward, land is to be sold at auction to the highest bidder.
- February 6 – France's Parliament votes a sentence of civil degradation, depriving Pierre Beaumarchais of all rights and duties of citizenship.
- February 7 – The volunteer fire company of Trenton, New Jersey, predecessor to the paid Trenton Fire Department created in 1892, is founded. In 1905, at 131 years, it claims to be the oldest continuously serving department in the U.S.
- February 24 – The Province of Massachusetts Bay House of Representatives votes, 92 to 8, to impeach Superior Court Chief Justice Peter Oliver, but Provincial Governor Thomas Hutchinson refuses to allow the trial to proceed.
- March 10 – The Boston Journal makes the first reference to the "Stars and Stripes" flag to symbolize the American colonies, reporting that "The American ensign now sparkles a door which shall shortly flame from the skies."
- March 31 – Intolerable Acts: The British Parliament passes the Boston Port Act, closing the port of Boston, Massachusetts as punishment for the Boston Tea Party.
- April 17 – The first avowedly Unitarian congregation, Essex Street Chapel, is founded in London by Theophilus Lindsey.
- April 19 – The premiere of Iphigénie en Aulide by Christoph Willibald Gluck sparked a huge controversy, almost a war, such as has not been seen in Paris since the Querelle des Bouffons.
- May 10 – Louis XVI becomes King of France, following the death of his grandfather, Louis XV.
- May 17 – The colony of Rhode Island and Providence Plantations issues the first call for an "Intercolonial Congress" that eventually is set up as the Continental Congress.
- May 19 – Shakers Ann Lee and eight followers sail from Liverpool, England for colonial America.
- June 2 – Intolerable Acts: A new Quartering Act, requiring American colonists to provide better housing for British soldiers upon demand, is passed.
- June 16–17 – English explorer James Cook becomes the first European to sight (and name) Palmerston Island in the South Pacific Ocean.
- June 20 (June 9 O.S.) – Russo-Turkish War (1768–74): Battle of Kozludzha – The Imperial Russian Army, led by Alexander Suvorov, routs numerically superior Ottoman Empire forces.
- June 22 – The Parliament of Great Britain passes the Quebec Act, setting out rules of governance for the colony of Quebec in British North America, enlarging its territory as far south as Ohio and granting freedom of religion for Roman Catholics.
- July 21 – Russia and the Ottoman Empire sign the Treaty of Küçük Kaynarca with Russian victory, ending six years of war. The treaty gives Russia the right to intervene in Ottoman politics, to protect its Christian subjects.
- August 1 – The element oxygen is discovered for the third (and last) time – the second quantitatively, following the somewhat earlier work of Carl Wilhelm Scheele (1771–1772) by Joseph Priestley, who publishes the fact in 1775, and so names the element (and usually gets all the credit, because his work was published first).
- August 6 – Ann Lee and the Shakers arrive in America and settle in New York.
- September 1 – Powder Alarm: Thomas Gage, royal governor of the Province of Massachusetts Bay, orders British soldiers to remove gunpowder from a magazine, causing Patriots to prepare for war.
- September 4 – English explorer James Cook becomes the first European to sight (and name) the island of New Caledonia in Melanesia.
- September 5 – The First Continental Congress assembles in Philadelphia.
- September 15 – Yemelyan Pugachev, leader of Pugachev's Rebellion against Russia by the Yaik Cossacks, is betrayed by his own men after returning to Yaitsk now Oral, Kazakhstan.
- September 21 – George Mason and George Washington found the Fairfax County Militia Association, a military unit independent of British control.
- September 29 – Johann Wolfgang von Goethe's semi-autobiographical epistolary novel The Sorrows of Young Werther (Die Leiden des jungen Werthers) (written January–March) is published anonymously in Leipzig, Germany; it is influential in the Sturm und Drang movement and Romanticism.
- October 10
- October 14 – The Continental Congress in America adopts the first "Declaration of Rights", with 10 principles.
- October 20 – Theater performances in the American colonies halt on recommendation of the Continental Congress that the member colonies "discountenance and discourage all horse racing and all kinds of gaming, cock fighting, exhibitions of shows, plays, and other expensive diversions and entertainments."
- October 21 – The word Liberty is first displayed on a flag raised by colonists in Taunton, Massachusetts, in defiance of British rule in Colonial America.
- October 25 – The Edenton Tea Party takes place in North Carolina, marking the first major gathering of women in support of the American cause.
- October 26 – The first Continental Congress adjourns in Philadelphia.
- November 4 –The Maryland Jockey Club follows a recommendation of the Continental Congress and cancels its race schedule. The decision sets a precedent for other jockey clubs in the colonies, and no major races are held until the end of the American Revolution.
- November 10 – 1774 British general election: Voting for the House of Commons concludes in Great Britain, and Lord North retains the office of Prime Minister as his Tory coalition wins 343 of the 558 seats. Henry Seymour Conway's Whig Party wins the other 215 seats.
- November 15 – The government of the Republic of Venice allows adventurer and ladies' man Giacomo Casanova to return home after a 17-year absence.
- November 20 – Daniel Boone retires from the Virginia colonial militia in order to devote his full time to establishing a settlement in Kentucky.
- November 25 – Salawat Yulayev, the leader of the Bashkirs rebellion against the Russian government, is captured, bringing an end to the insurrection.
- November 26 – English chemist Joseph Priestley becomes the first person to discover and identify sulfur dioxide.
- November 27 – Spanish Navy Captain Domingo de Bonechea arrives at Tahiti in the ship Aguila and tries unsuccessfully to claim it for Spain and to convert the Tahitians to the Roman Catholic faith.
- November 30
- Parliament adjourns in Great Britain, but declines to authorize any action against the rebellious American colonies, despite an address the day before by King George III and Prime Minister North.
- Thomas Paine, a native of England, arrives in America at the age 37 and soon becomes an influential advocate for the colonies' independence.
- December 1 – A boycott called by the Continental Congress goes into effect, as participating merchants and supporters cease the importation or consumption of products from Great Britain, Ireland or the British West Indies.
- December 6 – Archduchess Maria Theresa, the ruler of Austria, Hungary and Croatia, signs the General School Ordinance providing for education for both males and females and setting compulsory education for children aged six through 12.
- December 9 – The two month long Siege of Melilla begins as armies led by the Sultan of Morocco, Mohammed ben Abdallah, attack the North African Spanish colony of Melilla (which remains a part of Spain into the 21st century).
- December 23 – King Louis XVI of France issues a declaration that, for the first time, protects "the free commerce of meat during Lent" to support the needs of "the poor whose infirmity requires them to eat meat."
The American Revolution begins this year, with the first military engagement being the April 19 Battles of Lexington and Concord on the day after Paul Revere's now-legendary ride. The Second Continental Congress takes various steps toward organizing an American government, appointing George Washington commander-in-chief (June 14), Benjamin Franklin postmaster general (July 26) and creating a Continental Navy (October 13) and a Marine force (November 10) as landing troops for it, but as yet the 13 colonies have not declared independence, and both the British (June 12) and American (July 15) governments make laws. On July 6, Congress issues the Declaration of the Causes and Necessity of Taking Up Arms and on August 23, King George III of England declares the American colonies in rebellion, announcing it to parliament on November 10. On June 17, two months into the colonial siege of Boston, at the Battle of Bunker Hill, just north of Boston, British forces are victorious, but only after suffering severe casualties and after Colonial forces run out of ammunition, Fort Ticonderoga is taken by American forces in New York Colony's northern frontier, and American forces unsuccessfully invade Canada, with an attack on Montreal defeated by British forces on November 13 and an attack on Quebec repulsed December 31.
Human knowledge and mastery over nature advances when James Watt builds a successful prototype of a steam engine, and a scientific expedition continues as Captain James Cook claims the South Georgia and South Sandwich Islands in the south Atlantic Ocean for Britain. Nature's power over humanity is dramatically demonstrated when the Independence Hurricane (August 29 – September 13) devastates the east coast of North America, killing 4,173, and when, on the western side of the North American continent, Tseax Cone erupts in the future British Columbia, as well as when a smallpox epidemic begins in New England. Smallpox was then cured by Edward Jenner.
- January – The Habsburg Monarchy forces the Ottoman Empire to cede Bukovina to its rule.
- January 5 – Wolfgang Amadeus Mozart finishes a Sonata for Keyboard in C.
- January 17 – Second voyage of James Cook: Captain James Cook takes possession of South Georgia for the Kingdom of Great Britain.
- February 9 – American Revolution: The Parliament of Great Britain declares the Province of Massachusetts Bay to be in rebellion.
- February 15 – Pope Pius VI succeeds Pope Clement XIV as the 250th pope.
- March 6 – Raghunathrao, Peshwa of the Maratha Empire in India, signs the Treaty of Surat with the British Governor-General Warren Hastings in Bombay ceding the territories of Salsette and Bassein to the British East India Company along with part of the revenues from Surat and Bharuch districts in return for military assistance. This leads to the First Anglo-Maratha War fought between the British and the Marathas, ending with the Treaty of Salbai in 1782.
- March 17 – Catherine the Great of Russia issues a manifesto prohibiting freed serfs from being returned to serfdom.
- March 23 – American Revolution: Patrick Henry, a delegate to the Second Virginia Convention after the Virginia House of Burgesses was disbanded by the Royal Governor, delivers his "Give me Liberty, or give me Death!" speech at St. John's Church in Richmond, Virginia.
- April 18 – American Revolution: Paul Revere and William Dawes, instructed by Dr. Joseph Warren, ride from Boston to Lexington to warn John Hancock and Sam Adams that British forces are coming to take them prisoner and to seize colonial weapons and ammunition in Concord.
- April 19 – American Revolution: Hostility between Britain and its American colonies explodes into bloodshed at the Battles of Lexington and Concord igniting the American Revolution.
- May 10
- May 17 – American Revolution: The Continental Congress bans trade with Canada.
- June 11 – Battle of Machias, the first naval engagement of the American Revolutionary War.
- June 12 – American Revolution:
- June 14 – American Revolution: The Continental Congress names George Washington as commander of the Continental Army.
- June 16 – Post of Chief Engineer of the Continental Army created.
- June 17 – American Revolution: Two months into the colonial siege of Boston, British open fire on Breed's Hill on Charles Town Peninsula. After 3 charges, the British take the hill in the misnamed Battle of Bunker Hill.
- June 19 – Post of Commanding General was created by the Continental Congress.
- July 3 – American Revolution: George Washington takes command of the 17,000-man Continental Army at Cambridge.
- July 5 – American Revolution: The Continental Congress sends the Olive Branch Petition, hoping for a reconciliation.
- July 6 – American Revolution: The Continental Congress issues Declaration of the Causes and Necessity of Taking Up Arms, which contains the words: "Our cause is just. Our union is perfect... being with one mind resolved to die freemen rather than to live slaves...".
- July 26 – The Second Continental Congress appoints Benjamin Franklin to be the first Postmaster General of what later becomes the United States Post Office Department.
- July 30 – Second voyage of James Cook: HMS Resolution (1771) anchors off the south coast of England, Captain Cook having completed the first east-about global circumnavigation.
- August 18 – Tucson was founded.
- August 21 – American Revolution – Siege of Fort St. Jean: American rebels launch an invasion of Canada.
- August 23 – American Revolution: Refusing to even look at the Olive Branch Petition, King George issues a Proclamation of Rebellion against the American colonies.
- August 29 – September 12 – The Independence Hurricane from South Carolina to Nova Scotia kills 4,170, mostly fishermen and sailors.
- September 25 – American Revolution: Siege of Fort St. Jean – Battle of Longue-Pointe: Thirteen Colonies revolutionary forces under Maj. Ethan Allen attack Montreal in Quebec, commanded by British General Guy Carleton. Allen's forces are defeated, and Allen himself is captured and held on British ships until he is later released.
- October – The Sayre Plotters attempt to kidnap George III of the United Kingdom.
- October 13 – American Revolution: The Continental Congress orders the establishment of the Continental Navy (later the United States Navy).
- October 26 – American Revolution: George III announces to Parliament that the American colonies are in an uprising and must be dealt with accordingly.
- November – American Revolution: Colonel Richard Richardson's South Carolina revolutionaries march through Ninety-Six District in what becomes known as the Snow Campaign, effectively ending all major support for the Loyalist cause in the backcountry of South Carolina.
- November 10 – American Revolution: The Continental Congress passes a resolution creating the Continental Marines to serve as landing troops for the recently created Continental Navy (the Marines are disbanded at end of the war in April 1783 but reformed on July 11, 1798 as the United States Marine Corps).
- November 13 – American Revolution – Battle of Montreal: American forces under Brigadier General Richard Montgomery capture Montreal. British General Guy Carleton escapes to Quebec.
- November 17 – John Murray, 4th Earl of Dunmore offers freedom to slaves who join the loyalist army, thus losing the support of most planters, who see slaves as their vital livelihood.
- December 5 – American Revolution: Henry Knox begins his journey to Cambridge, Massachusetts with the artillery that has been captured from Fort Ticonderoga.
- December 31 – American Revolution: Battle of Quebec: British forces repulse an attack by Continental Army generals Richard Montgomery and Benedict Arnold at Quebec.
- May 1 – Adam Weishaupt founds the Illuminati in Ingolstadt, Bavaria.
- May 4 – Rhode Island becomes the first American colony to renounce allegiance to King George III of Great Britain.
- May 15–26 – American Revolution – Battle of The Cedars: British forces skirmish with the American Continental Army around Les Cèdres, Quebec.
- June 6 – A fire destroys major parts of the town of Askersund, Sweden.
- June 7 – American Revolution – Richard Henry Lee of Virginia proposes to the Second Continental Congress (meeting in Philadelphia) that "these united colonies are, and of right ought to be, free and independent states."
- June 8 – American Revolution – Battle of Trois-Rivières: The invading American Continental Army is driven back at Trois-Rivières, Quebec.
- June 11 – American Revolution – The Continental Congress appoints a Committee of Five to draft a Declaration of Independence.
- June 12 – American Revolution – The Virginia Declaration of Rights (by George Mason) is adopted by the Virginia Convention of Delegates.
- June 15 – American Revolution – Delaware Separation Day: The Delaware General Assembly votes to suspend government under the British Crown.
- June 17 – Lt. José Joaquín Moraga leads a band of colonists from Monterey Presidio, landing on June 29 and, with Father Francisco Palóu, constructing the Mission San Francisco de Asís ("Mission Dolores") of the new Presidio of San Francisco, the oldest surviving building in the modern-day city.
- June 28 – American Revolutionary War – Battle of Sullivan's Island: South Carolina militia repel a British attack on Charleston.
- June 29 – American Revolutionary War – Battle of Turtle Gut Inlet: The American Continental Navy successfully challenges the British Royal Navy blockade off New Jersey.
- July 2 – American Revolution – The final U.S. Declaration of Independence (with minor revisions) is written. The Continental Congress passes the Lee Resolution.
- July 4 – American Revolution – United States Declaration of Independence: The Continental Congress ratifies the declaration by the United States of its independence from the Kingdom of Great Britain.
- July 8 – American Revolution – The Liberty Bell rings in Philadelphia, for the first public reading of the Declaration of Independence.
- July 9 – American Revolution – An angry mob in New York City topples the equestrian statue of George III of Great Britain in Bowling Green.
- July 12 – Captain James Cook sets off from Plymouth, England, in HMS Resolution on his third voyage, to the Pacific Ocean and Arctic, which will be fatal.
- July 21 – Mozart's Serenade No. 7 (the "Haffner") is first performed in Salzburg, Austria.
- July 29 – Francisco Silvestre Vélez de Escalante, Francisco Atanasio Domínguez, and eight other Spaniards set out from Santa Fe, on an eighteen-hundred mile trek through the American Southwest. They are the first Europeans to explore the vast region between the Rockies and the Sierras.
- August 2 – Most of the American colonies ratify the Declaration of Independence.
- August 15 – American Revolution – The first Hessian troops land on Staten Island, to join British forces.
- August 27 – American Revolution – Battle of Long Island: Washington's troops are routed in Brooklyn by the British, under William Howe.
- August – The guild organisation Marchandes de modes is founded in Paris.
- January 2 – American Revolutionary War: American forces under the command of George Washington repulsed a British attack at the Battle of the Assunpink Creek near Trenton, New Jersey.
- January 3 – American Revolutionary War – Battle of Princeton: American general George Washington's army defeats British troops.
- January 11 – American Revolutionary War – Battle of the Assunpink Creek: American general George Washington's army repulses a British attack by Lieutenant General Charles Cornwallis, in a second battle at Trenton, New Jersey.
- January 12 – Mission Santa Clara de Asís is founded in what becomes Santa Clara, California.
- January 15 – Vermont declares its independence from New York, becoming the Vermont Republic, an independent country, a status it retains until it joins the United States as the 14th state in 1791.
- January 20 – The Continental Congress approves a resolution "that an authentic copy, with names of the signers of the Declaration of independence, be sent to each of the United States.
- February 5 – Under the 1st Constitution of Georgia, 8 counties were chartered: Burke, Camden, Chatham, Effingham, Glynn, Liberty, Richmond, and Wilkes. This dissolved the existing parishes of St. George, St. Mary's, St. Thomas, St. Phillip, Christ Church, St. David, St. Matthews, St. Andrew, St. James, St. Johns, and St. Paul.
- February 24 – King Joseph I of Portugal dies, and is succeeded by his brother and son-in-law Peter III of Portugal, and his daughter Maria I of Portugal.
- March 4 – The Fourth Continental Congress, with John Hancock as President, begins a 199 day session in Philadelphia, lasting until September 18.
- March 29–30 – Third voyage of James Cook: English explorer Captain Cook discovers Mangaia and Atiu in the Cook Islands.
- April 1 – Friedrich Maximilian Klinger's play Sturm und Drang is premiered by the Seyler Theatre Company in Leipzig, giving its name to the whole Sturm und Drang movement in German literature.
- April 13 – American Revolutionary War – Battle of Bound Brook: A British and Hessian force led by Charles Cornwallis surprises a Continental Army outpost in New Jersey, commanded by Major General Benjamin Lincoln.
- April 27 – American Revolutionary War – Battle of Ridgefield: The British Army defeats Patriot militias, galvanizing resistance in the Connecticut Colony.
- May 8 – Richard Brinsley Sheridan's comedy of manners, The School for Scandal, is first performed at the Theatre Royal, Drury Lane in London.
- May 16 – Lachlan McIntosh and Button Gwinnett shoot each other during a duel near Savannah, Georgia. Gwinnett, a signer of the United States Declaration of Independence, dies three days later.
- June 13 – American Revolution: The Marquis de Lafayette lands near Georgetown, South Carolina, to help the Continental Congress train its army.
- July 8 – The 1777 Constitution of Vermont is signed, officially abolishing slavery.
- July 6 – American Revolutionary War – Siege of Fort Ticonderoga: After a bombardment by British artillery under General John Burgoyne, American forces retreat from Fort Ticonderoga, New York.
- July 7 – American Revolutionary War – Battle of Hubbardton: British forces capture over 200 of the American rearguard, from Fort Ticonderoga.
- August 6 – American Revolutionary War – Battle of Oriskany: Loyalists gain a tactical victory over Patriots; Iroquois fight on both sides.
- August 16 – American Revolutionary War – Battle of Bennington: British and Brunswicker forces are decisively defeated by American troops.
- August 22 – American Revolutionary War – The Siege of Fort Stanwix is ended by withdrawal of British forces, following a ruse by Benedict Arnold to persuade them that a much larger force is arriving.
- September 3 – American Revolutionary War – Battle of Cooch's Bridge: British and Hessian forces defeat an American militia, in a minor skirmish in New Castle County, Delaware.
- September 11 – American Revolutionary War – Battle of Brandywine: The British gain a major victory in Chester County, Pennsylvania.
- September 19 – American Revolutionary War – First Battle of Saratoga (Battle of Freeman's Farm): Patriot forces withstand a British attack at Saratoga, New York.
- September 26 – American Revolutionary War – British troops occupy Philadelphia; members of the Continental Congress flee to Lancaster, Pennsylvania where they meet and hold a one day session as the Fifth Congress before fleeing again.
- September 30 – American Revolutionary War – The Sixth Continental Congress opens its session at York, Pennsylvania, and continues for 272 days until June 27, 1778.
- October 4 – American Revolutionary War – Battle of Germantown: Troops under George Washington are repelled by British troops under Sir William Howe.
- October 6 – American Revolutionary War – Battle of Forts Clinton and Montgomery: British troops capture Fort Clinton and Fort Montgomery (Hudson River), and are able to dismantle the Hudson River Chain.
- October 7 – American Revolutionary War – Second Battle of Saratoga (Battle of Bemis Heights): British General John Burgoyne is defeated by American troops.
- October 17 – American Revolutionary War – Battle of Saratoga: British General John Burgoyne surrenders to the American troops.
- November 15 – American Revolution: After 16 months of debate, the Continental Congress approves the Articles of Confederation, in the temporary American capital at York, Pennsylvania.
- November 17 – American Revolution: The Articles of Confederation are submitted to the states for ratification.
- November 29 – San Jose, California is founded. It is the first pueblo in Spanish Alta California.
- December 18 – The United States celebrates its first Thanksgiving, marking October's victory by the American rebels over British General John Burgoyne at Saratoga.
- December 19 – American Revolutionary War – George Washington's Continental Army goes into winter quarters at Valley Forge, Pennsylvania.
- December 24 – Third voyage of James Cook: English explorer Captain Cook locates Kiritimati (Christmas Island).
- December 30 – Maximilian III Joseph, Elector of Bavaria dies and is succeeded by his distant cousin Charles Theodore, Elector of Bavaria.
- April 7 – British Prime Minister William Pitt, delivers his last speech to Parliament, and speaks to the House of Lords "passionately but incoherently against the granting of independence" to the American colonies, but collapses during the debate, and dies five weeks later. 
- April 12 – King George III appoints the five-member Carlisle Peace Commission to present peace terms to negotiate an end to the rebellion of Britain's 13 American colonies. 
- April 30 – The 1,800 feet (550 m) long Hudson River Chain, designed to prevent British ships from moving up the river toward West Point, New York is stretched across the river and anchored by an engineering team under the direction of Captain Thomas Machin. 
- May 12 – Heinrich XI, Prince Reuss of Greiz is elevated to Prince of the Principality of Reuss-Greiz by Joseph II, Holy Roman Emperor – it is during Heinrich XI's rule in 1778, that the first appearance of the national colors of modern Germany are present on a flag that closely resembles the modern Flag of Germany, to occur anywhere within what today comprises Germany.
- May 30 – Benedict Arnold signs the U.S. Oath of Allegiance at Valley Forge.
- June 24 – A total solar eclipse takes place across parts of North America, from Texas to Virginia.
- June 28 – American Revolutionary War – Battle of Monmouth: George Washington's Continental Army battles British general Sir Henry Clinton's army to a draw, near Monmouth County, New Jersey.
- June – The Anglo-French War (1778–83) begins.
- July 3 – American Revolutionary War – The Wyoming Massacre takes place near Wilkes-Barre, Pennsylvania, ending in a terrible defeat of the local colonists.
- July 4 – American Revolutionary War – George Rogers Clark takes Kaskaskia.
- July 10 – Louis XVI of France declares war on the Kingdom of Great Britain.
- July 27 – American Revolutionary War – First Battle of Ushant – British and French fleets fight to a standoff.
- August 3 – The La Scala Opera House opens in Milan, with the première of Antonio Salieri's Europa riconosciuta.
- August 26 – Triglav, at 2,864 metres (9,396 ft) above sea level the highest peak of Slovenia, is ascended for the first time by four men: Luka Korošec, Matevž Kos, Štefan Rožič, and Lovrenc Willomitzer, on Sigmund Zois' initiative.
- August 29 – American Revolutionary War – The tactically inconclusive Battle of Rhode Island takes place, after which the Continental Army abandons its position on Aquidneck Island.
- September – The Massachusetts Banishment Act, providing punishment for Loyalists, is passed.
- September 7 – American Revolutionary War – Invasion of Dominica: The French capture the British fort there, before the latter is aware that France has entered the war in the Franco-American alliance.
- September 17 – The Treaty of Fort Pitt is signed, the first formal treaty between the United States and a Native American tribe (the Lenape or Delaware).
- September 19 – The Continental Congress passes the first budget of the United States.
- October 12 – The Continental Congress advises the 13 member states to suppress "theatrical entertainments, horse-racing, gaming, and such other diversions as are productive of idleness, dissipation, and general depravity of principles and manners." 
- January 11 – British troops surrender to the Marathas in Wadgaon, India, and are forced to return all territories acquired since 1773.
- January 11 – Ching-Thang Khomba is crowned King of Manipur.
- January 22 – American Revolutionary War – Claudius Smith is hanged at Goshen, Orange County, New York for supposed acts of terrorism upon the people of the surrounding communities.
- January 29 – After a second petition for partition from its residents, the North Carolina General Assembly abolishes Bute County, North Carolina (established 1764) by dividing it and naming the northern portion Warren County (for Revolutionary War hero Joseph Warren), and the southern portion Franklin County (for Benjamin Franklin). The General Assembly also establishes Warrenton (also named for Joseph Warren) to be the seat of Warren County, and Louisburg (named for Louis XVI of France) to be the seat of Franklin County.
- February 12 – Lieutenant Colonel Francisco Bouligny arrives with Malagueño colonists at Bayou Teche, to establish the city of New Iberia, Louisiana.
- February 14 – Captain James Cook is killed on the Sandwich Islands, on his third voyage.
- March 10 – The Treaty of Aynalıkavak is signed between Ottoman Turkey and the Russian Empire, regarding the Crimean Khanate.
- July 16 – American Revolutionary War – United States forces, led by General Anthony Wayne, capture Stony Point, New York from British troops.
- July 16 – Declaratory Rescript of the Illyrian Nation issued in order to regulate organization of Eastern Orthodox Church in Habsburg Monarchy.
- July 20 – Tekle Giyorgis I begins the first of his five reigns as Emperor of Ethiopia.
- July 22 – Battle of Minisink: The Goshen Militia is destroyed by Joseph Brant's forces.
- July 24 – American Revolutionary War – American forces, led by Commodore Dudley Saltonstall, launch the Penobscot Expedition in what is now Castine, Maine, resulting in the worst naval defeat in U.S. history (until Pearl Harbor).
- July – The Great Siege of Gibraltar (fourteenth and last military siege) begins. This is an action by French and Spanish forces to wrest control of Gibraltar from the established British garrison. The garrison, led by George Augustus Eliott (later 1st Baron Heathfield of Gibraltar), survives all attacks and a blockade of supplies.
- September 14–15 – American Revolutionary War – Little Beard's Town, a loyalist stronghold, is burnt by the Sullivan Expedition.
- September 23 – American Revolutionary War – Battle of Flamborough Head – The American ship Bonhomme Richard, commanded by John Paul Jones, engages the British ship HMS Serapis. The Bonhomme Richard sinks, but the Americans board the Serapis and other vessels, and are victorious.
- September 28 – Samuel Huntington is elected as the seventh President of the Continental Congress 
- Industrial Revolution in England:
- The city of Tampere, Finland, is founded.
- A joint Spanish-Portuguese survey of the Amazon basin begins to determine the boundary between the colonial possessions in South America; it continues until 1795.