MERCIA, one of the kingdoms of Anglo-Saxon England. The original kingdom seems to have lain in the upper basin of the Trent, comprising the greater part of Staffordshire, Derbyshire and Nottinghamshire and the northern parts of Warwickshire and Leicestershire. The name (Merce) seems to denote men of the March, and presumably was first applied when this district bor dered upon the Welsh. In later times Mercia successively absorbed all the other territories between the Humber and the Thames except East Anglia, and some districts even beyond the Thames.
The origin of the kingdom is obscure. The royal family, accord ing to Felix, Life of St. Guthlac, were called Iclingas. Icel, their ancestor, may have been the founder of the kingdom, but nothing is known of him. The family, however, claimed descent from the ancient kings of Angle (cf. Offa I. and Wermund). The first Mercian king of whom we have any record was Cearl, who appar ently reigned about the beginning of the 7th century, and whose daughter Cwoenburg married Edwin, king of Deira. During Edwin's reign Mercia was subject to his supremacy, though it may have been governed throughout by princes of its own royal family. Its first prominent appearance in history may be dated in 633, when the Mercian prince Penda joined the Welsh king Cadwallon in overthrowing Edwin. According to the Saxon Chronicle, Penda began to reign in 626, and fought against the West Saxons at Ciren cester in 628. In the Mercian regnal tables, however, be is assigned a reign of only twenty-one years, which, as his death took place in 654 or 655, would give 634 as the date of his accession, pre sumably on the overthrow of Edwin, or perhaps on that of Cad wallon. During the reign of Oswald Penda clearly reigned under the suzerainty of that king. In 642, however, Oswald was slain by Penda in a battle at a place called Maserfeld, which has not been identified with certainty. During the early part of Oswio's reign the Northumbrian kingdom was repeatedly ravaged by the Mercians, and on one occasion (before 651) Penda almost captured the Nor thumbrian royal castle at Bamborough. At the same time he extended his influence in other directions, and expelled from the throne of Wessex Coenwalh, who had divorced his sister. Indeed, at this time nearly all the English kingdoms must have acknowl edged his supremacy. The Middle Angles, whose territory includ ed the counties of Northampton, Rutland, Huntingdon, and parts of Bedfordshire, Cambridgeshire, Leicestershire and Lincolnshire, formed a dependent principality under his son Peada. At this time also the territory corresponding to the modern counties of Cheshire, Shropshire and Herefordshire seems to have been occu pied. The last of these counties is said some time later to have been under the government of another son of Penda, named Mere wald. In 654 or 655 Penda again invaded Northumbria, with a huge army divided into thirty legiones, each under a royal prince, among whom were Aethelhere, king of East Anglia, and several Welsh kings. He was slain, however, by Oswio, at a river called the Winwaed. Mercia then came again under Northumbrian rule.
Peada, the eldest son of Penda, was allowed to govern the part south of the Trent, while north Mercia was put in charge of Northumbrian officials. Penda, although he did not prohibit the preaching of Christianity, had remained a heathen to the end of his life. His death was followed by the conversion of his kingdom. Peada had embraced Christianity on his marriage with a daughter of Oswio, and under him the first Mercian bishopric was founded. Shortly afterwards Peada was murdered, but in 658 the Mercians rose under his younger brother Wulfhere and threw off the Northumbrian supremacy.
Wulfhere seems to have been a vigorous ruler, for he extended the power of Mercia as far as it had reached in the days of his father, and even farther. According to the Chronicle he invaded Wessex as far as the Berkshire Downs in 661. At the same time he conquered the Isle of Wight, which he gave to Aethelwalh, king of Sussex. Between 661 and 665 he was defeated by the Northumbrian king Ecgfrith and had to give up Lindsey. In 675 he again fought with the West Saxons under Aescwine, and shortly afterwards died. His brother Aethelred, who succeeded him, in vaded Kent in the following year, and in 679 fought a battle on the Trent against Ecgfrith, by which he recovered Lindsey. After this, however, we hear little of Mercian interference with the other kingdoms for some time; and since it is clear that dur ing the last 15 years of the 7th century Wessex, Essex, Sussex and Kent were frequently involved in strife, it seems likely that the Mercian king had somewhat lost hold over the south of Eng land. In 704 Aethelred resigned the crown and became a monk, leaving his kingdom to Coenred, the son of Wulfhere. Coenred also abdicated five years later and went to Rome. Ceolred, the son of Aethelred, who succeeded, fought against the West Saxon king Ine in 715. On his death in the following year Aethelbald, a dis tant relative, came to the throne, and under him Mercian suprem acy was fully restored over all the English peoples south of the Humber. After his murder in 757 the Mercian throne was held for a short time by Beornred. He was expelled the same year by Offa, who soon restored the power of Mercia, which seems to have suffered some diminution during the later years of Aethelbald. Offa's policy was apparently the extinction of the dependent king doms. In his reign the dynasties of Kent, Sussex and the Hwicce seem to have disappeared, or at all events to have given up the kingly title. In 787 he associated his son Ecgfrith with him in the kingdom, and after his death (796) Ecgfrith reigned alone for a few months. On the death of Ecgfrith the throne passed to Coen wulf, a descendant of Pybba, father of Penda. In 821 Coenwulf was succeeded by his brother Ceolwulf, who was deprived of the throne in 823, being succeeded by Beornwulf. In 825 Beornwulf was defeated by Ecgberht, king of Wessex, and in the same year he was overthrown and slain by the East Angles. The supremacy now passed to Wessex.