In the early Middle Ages
Mercia's exact evolution at the start of the Anglo-Saxon era remains more obscure than that of Northumbria, Kent, or even Wessex. Mercia developed an effective political structure and adopted Christianity later than the other kingdoms. Archaeological surveys show that Angles settled the lands north of the River Thames by the 6th century. The name "Mercia" is Old English for "boundary folk" (see Welsh Marches), and the traditional interpretation is that the kingdom originated along the frontier between the native Welsh and the Anglo-Saxon invaders. However, P. Hunter Blair argued an alternative interpretation: that they emerged along the frontier between Northumbria and the inhabitants of the Trent river valley.
While its earliest boundaries will never be known, there is general agreement that the territory that was called "the first of the Mercians" in the Tribal Hidage covered much of south Derbyshire, Leicestershire, Nottinghamshire, Northamptonshire, Staffordshire and northern Warwickshire.
The earliest person named in any records as a king of Mercia is Creoda, said to have been the great-grandson of Icel. Coming to power around 584, he built a fortress at Tamworth which became the seat of Mercia's kings. His son Pybba succeeded him in 593. Cearl, a kinsman of Creoda, followed Pybba in 606; in 615, Cearl gave his daughter Cwenburga in marriage to Edwin, king of Deira, whom he had sheltered while he was an exiled prince.
The Mercian kings were the only Anglo-Saxon Heptarchy ruling house known to claim a direct family link with a pre-migration Continental Germanic monarchy.
Penda and the Mercian Supremacy
Mercia and the main Anglo-Saxon kingdoms at about 600
The next Mercian king, Penda, ruled from about 626 or 633 until 655. Some of what is known about Penda comes from the hostile account of Bede, who disliked him – both as an enemy to Bede's own Northumbria and as a pagan. However, Bede admits that Penda freely allowed Christian missionaries from Lindisfarne into Mercia, and did not restrain them from preaching. In 633 Penda and his ally Cadwallon of Gwynedd defeated and killed Edwin, who had become not only ruler of the newly unified Northumbria, but bretwalda, or high king, over the southern kingdoms. When another Northumbrian king, Oswald, arose and again claimed overlordship of the south, he also suffered defeat and death at the hands of Penda and his allies – in 642 at the Battle of Maserfield. In 655, after a period of confusion in Northumbria, Penda brought 30 sub-kings to fight the new Northumbrian king Oswiu at the Battle of Winwaed, in which Penda in turn lost the battle and his life.
The battle led to a temporary collapse of Mercian power. Penda's son Peada, who had converted to Christianity at Repton in 653, succeeded his father as king of Mercia; Oswiu set up Peada as an under-king; but in the spring of 656 he was murdered and Oswiu assumed direct control of the whole of Mercia. A Mercian revolt in 658 threw off Northumbrian domination and resulted in the appearance of another son of Penda, Wulfhere, who ruled Mercia as an independent kingdom (though he apparently continued to render tribute to Northumbria for a while) until his death in 675. Wulfhere initially succeeded in restoring the power of Mercia, but the end of his reign saw a serious defeat by Northumbria. The next king, Æthelred, defeated Northumbria in the Battle of the Trent in 679, settling once and for all the long-disputed control of the former kingdom of Lindsey. Æthelred was succeeded by Cœnred, son of Wulfhere; both these kings became better known for their religious activities than anything else, but the king who succeeded them in 709, Ceolred, is said in a letter of Saint Boniface to have been a dissolute youth who died insane. So ended the rule of the direct descendants of Penda.
At some point before the accession of Æthelbald in 716 the Mercians conquered the region around Wroxeter, known to the Welsh as Pengwern or as "The Paradise of Powys". Elegies written in the persona of its dispossessed rulers record the sorrow at this loss.
A series of maps that illustrate the increasing hegemony of Mercia during the 8th century
The next important king of Mercia, Æthelbald, reigned from 716 to 757. For the first few years of his reign he had to face two strong rival kings, Wihtred of Kent and Ine of Wessex. But when Wihtred died in 725, and Ine abdicated in 726 to become a monk in Rome, Æthelbald was free to establish Mercia's hegemony over the rest of the Anglo-Saxons south of the Humber. Æthelbald suffered a setback in 752, when the West Saxons under Cuthred defeated him, but he seems to have restored his supremacy over Wessex by 757.
In July 2009, the Staffordshire Hoard of Anglo-Saxon gold was discovered by Terry Herbert in a field near Lichfield in Staffordshire. Lichfield functioned as the religious centre of Mercia. The artefacts have tentatively been dated by Svante Fischer and Jean Soulat to around AD 600–800. Whether the hoard was deposited by Anglo-Saxon pagans or Christians remains unclear, as does the purpose of the deposit.
Reign of Offa and rise of Wessex
A mention of Mercia in the Anglo-Saxon Chronicle
After the murder of Æthelbald by one of his bodyguards in 757, a civil war broke out which concluded with the victory of Offa, a descendant of Pybba. Offa (reigned 757 to 796) had to build anew the hegemony which his predecessor had exercised over the southern English, and he did this so successfully that he became the greatest king Mercia had ever known. Not only did he win battles and dominate Southern England, but also he took an active hand in administering the affairs of his kingdom, founding market towns and overseeing the first major issues of gold coins in Britain; he assumed a role in the administration of the Catholic Church in England (sponsoring the short-lived archbishopric of Lichfield, 787 to 799), and even negotiated with Charlemagne as an equal. Offa is credited with the construction of Offa's Dyke, which marked the border between Wales and Mercia.
Offa exerted himself to ensure that his son Ecgfrith of Mercia would succeed him, but after Offa's death in July 796 Ecgfrith survived for only five months, and the kingdom passed to a distant relative named Coenwulf in December 796. In 821 Coenwulf's brother Ceolwulf succeeded to the Mercian kingship; he demonstrated his military prowess by his attack on and destruction of the fortress of Deganwy in Gwynedd. The power of the West Saxons under Egbert (King of Wessex from 802 to 839) grew during this period, however, and in 825 Egbert defeated the Mercian king Beornwulf (who had overthrown Ceolwulf in 823) at Ellendun.
The Battle of Ellendun proved decisive. Beornwulf was slain while suppressing a revolt amongst the East Angles, and his successor, a former ealdorman named Ludeca (reigned 826-827), met the same fate. Another ealdorman, Wiglaf, subsequently ruled for less than two years before Egbert of Wessex drove him out of Mercia. In 830 Wiglaf regained independence for Mercia, but by this time Wessex had clearly become the dominant power in England. Circa 840 Beorhtwulf succeeded Wiglaf.
Arrival of the Danes
The Five Boroughs and English Mercia in the early 10th century
In 852, Burgred came to the throne and with Ethelwulf of Wessex subjugated North Wales. In 868, Danish invaders occupied Nottingham. The Danes drove Burgred from his kingdom in 874 and Ceolwulf II took his place. In 877 the Danes seized the eastern part of Mercia, which became part of the Danelaw. Ceolwulf, the last king of Mercia, was left with the western half, and he reigned until 879. From about 883 until 911 Æthelred, Lord of the Mercians, ruled Mercia under the overlordship of Wessex. All coins struck in Mercia after the disappearance of Ceolwulf in c.879 were in the name of the West Saxon king. Æthelred had married Æthelflæd, daughter of Alfred the Great of Wessex, and she assumed power when her husband became ill at some time in the last ten years of his life.
After Æthelred's death in 911, Æthelflæd ruled as ‘Lady of the Mercians’ but Alfred's successor, Edward the Elder, took control of London and Oxford, which Alfred had placed under Æthelred's control. She and her brother continued Alfred's policy of building fortified burhs, and in 917-18 they were able to conquer the southern Danelaw in East Anglia and Danish Mercia.
Loss of independence
When Æthelflæd died in 918, Ælfwynn, her daughter by Æthelred, succeeded as 'Second Lady of the Mercians', but within six months Edward had deprived her of all authority in Mercia and taken her into Wessex.
References to Mercia and the Mercians continue through the annals recording the reigns of Æthelstan and his successors. Æthelstan himself was raised in Mercia and became its king before he was king of Wessex. In Winchester, there was even an attempt to blind Æthelstan as he was seen as an outsider. In 975, King Edgar is described as “friend of the West Saxons and protector of the Mercians”.
A separate political existence from Wessex was briefly restored in 955–959, when Edgar became king of Mercia, and again in 1016, when the kingdom was divided between Cnut and Edmund Ironside, Cnut taking Mercia.
The last reference to Mercia by name is in the annal for 1017, when Eadric Streona was awarded the government of Mercia by Cnut. The later earls, Leofric, Ælfgar and Edwin, ruled over a territory broadly corresponding to historic Mercia, but the Chronicle does not identify it by name. The Mercians as a people are last mentioned in the annal for 1049.