Conflict between Great Britain and France broke out in 1754–1756 when the British attacked disputed French positions in North America, starting with a British ambush of a small French force at the Battle of Jumonville Glen on 28 May 1754, and extended across the colonial boundaries and the seizure of hundreds of French merchant ships at sea. Meanwhile, rising power Prussia was struggling with Austria for dominance within and outside the Holy Roman Empire in central Europe. In 1756, the major powers "switched partners".
Realising that war was imminent, Prussia pre-emptively struck Saxony and quickly overran it. The result caused uproar across Europe. Because of Austria's alliance with France to recapture Silesia, which had been lost in the War of the Austrian Succession, Prussia formed an alliance with Britain. Reluctantly, by following the imperial diet, which declared war on Prussia on 17 January 1757, most of the states of the empire joined Austria's cause. The Anglo-Prussian alliance was joined by smaller German states (especially the Electorate of Hanover). Sweden, seeking to re-gain Pomerania (most of which had been lost to Prussia in previous wars) joined the coalition, seeing its chance when all the major powers of Europe opposed Prussia. Spain, bound by the Pacte de Famille, intervened on behalf of France and together they launched an utterly unsuccessful invasion of Portugal in 1762. The Russian Empire was originally aligned with Austria, fearing Prussia's ambition on the Polish–Lithuanian Commonwealth, but switched sides upon the succession of Tsar Peter III in 1762.
Many middle and small powers in Europe, as in the previous wars, tried to steer clear away from the escalating conflict, even though they had interests in the conflict or with the belligerents. Denmark–Norway, for instance, was close to being dragged into the war on France's side when Peter III became Russian emperor and switched sides; Dano-Norwegian and Russian armies were close to ending up in battle, but the Russian emperor was deposed before war formally broke out. The Dutch Republic, a long-time British ally, kept its neutrality intact, fearing the odds against Britain and Prussia fighting the great powers of Europe, and even tried to prevent Britain's domination in India. Naples, Sicily, and Savoy, although sided with the Franco-Spanish alliance, declined to join the coalition under fear of British naval power. The taxation needed for war caused the Russian people considerable hardship, being added to the taxation of salt and alcohol begun by Empress Elizabeth in 1759 to complete her addition to the Winter Palace. Like Sweden, Russia concluded a separate peace with Prussia.
The war ended with the Treaty of Paris between France, Spain and Great Britain and the Treaty of Hubertusburg between Saxony, Austria and Prussia, in 1763.
The war was successful for Great Britain, which gained the bulk of New France in North America, Spanish Florida, some individual Caribbean islands in the West Indies, the colony of Senegal on the West African coast, and superiority over the French trading outposts on the Indian subcontinent. The Native American tribes were excluded from the settlement; a subsequent conflict, known as Pontiac's War, which was a small scale war between the indigenous tribe known as the Odawas and the English, where the Odawas claimed seven of the ten forts created or taken by the English to show them that they need to distribute land equally amongst their allies, was also unsuccessful in returning them to their pre-war status. In Europe, the war began disastrously for Prussia, but with a combination of good luck and successful strategy, King Frederick the Great managed to retrieve the Prussian position and retain the status quo ante bellum. Prussia emerged as a new European great power. Although Austria failed to retrieve the territory of Silesia from Prussia (its original goal), its military prowess was also noted by the other powers. The involvement of Portugal, Spain and Sweden did not return them to their former status as great powers. France was deprived of many of its colonies and had saddled itself with heavy war debts that its inefficient financial system could barely handle. Spain lost Florida but gained French Louisiana and regained control of its colonies, e.g., Cuba and the Philippines, which had been captured by the British during the war. France and Spain avenged their defeat during the American Revolutionary War, with hopes of destroying Britain's dominance once and for all.
The Seven Years' War was perhaps the first true world war, having taken place almost 160 years before World War I and influenced many major events later around the globe. The war restructured not only the European political order, but also affected events all around the world, paving the way for the beginning of later British world supremacy in the 19th century, the rise of Prussia in Germany (eventually replacing Austria as the leading German State), the beginning of tensions in British North America, as well as a clear sign of France's eventual turmoil. It was characterised in Europe by sieges and the arson of towns as well as open battles with heavy losses.