Mercia

Mercia, Anglo-Saxon kingdom, England, first recorded in the 6th century, located in the Midlands area, covering roughly the area of modern Staffordshire, Derbyshire, Nottinghamshire, and north Warwickshire. Initially occupying only the upper basin of the River Trent, Mercia became one of the most dominant of the early English kingdoms. It was ruthlessly extended by successive rulers, until by the end of the 8th century it covered all of England south of the Humber estuary to the Welsh border in the west, the border with East Anglia in the east, and the River Thames in the south. Its name is derived from the Old English Merce, meaning boundary folk.

The Mercians were Angles. The first of the Mercian kings of whom anything is known is Penda (d. 655), a belligerent warrior and champion of the old pagan religion, who constantly sought to extend his power. He won the kingship of Mercia in 632 through his successful invasion, together with Cadwallae of Wales, of the northern kingdom of Northumbria, whose king Edwin, newly converted to Christianity, he defeated and killed (633). The following year Penda was forced to relinquish Northumbria to Edwin's successor, Oswald; he did not regain it (and then only partially) until 641, when he again invaded the kingdom and defeated the Northumbrian king. Meanwhile Penda had been active in other directions. He made his son Peada sub-king of Middle Anglia and, although himself still a staunch pagan, allowed him to introduce Christianity there. The whole of East Anglia was eventually subjugated, and King Cenwalh of Wessex was driven from his kingdom for a period of three years (645-648). In 655 Penda was slain in battle by King Oswiu of Northumbria, whose territory he had invaded. Mercia did not regain its dominance until the next century.

Ethelbald, king of Mercia from 716, had by 731 gained control over all the English provinces south of the Humber and styled himself in his charters as rex Britanniae. He was murdered by a member of his household in 757, probably at the instigation of a rival. Under the rule of the next king, Offa, Mercia reached the zenith of its powers, with neighbouring rulers accepting its supremacy. Astutely, Offa married his daughters to the rulers of Northumbria and Wessex. Not since the departure of the Romans had England been one entity politically, and Offa's achievement of almost completing the reunification was complemented by the good relationships he forged with the Frankish ruler Charlemagne and with Pope Adrian I. One of his most lasting achievements was Offa's Dyke, a celebrated defensive system and boundary marker between England and Wales. He also established a new coinage which became a pattern for future English coins.

After Offa's death the power of Mercia gradually declined, due to the increasing dominance of Wessex from the south and, in particular, to Danish invasions in the east. At one time the kingdom was partly under Mercian, and partly under Danish, rule. In the early 10th century it accepted the supremacy of Athelstan of Wessex and thus became part of a united England.