MERCIA, one of the kingdoms of the Saxon Heptarchy. It occupied the central parts of England; was the country of the Middle Angles; absorbed large portions of the adjacent kingdoms; and survived all the other six, except Wessex. It was of varions extent, at varions periods; but, in a general and large view, it comprised all the territory S of the Humber, E of the Severn, N of the upper and middle reaches of the Thames, and W of a line drawn through Herts, Beds, Cambridge, Hunts, and Lincoln. The part's of it comprising Notts, Derby, and Cheshire, with the portions of Flint as far as to Offa's dyke, were called North Mercia; the parts comprising Worcestershire, Gloucestershire, and a portion of Warwickshire, were called Hwiccas, and were for some time independent; and the whole was designated by the Saxons themselves Myrcuaric or Meorclond. Cridda or Creoda founded the kingdom about 585, but was subject to Northumbria. Wibba succeeded in 595; and, together with subsequent successors, continued to own the supremacy of Northumbria. Penda succeeded in 626; became independent; took London and part of Wessex; and had his seat at Tamworth. Peada succeeded in 656; Wolfhere, or Wulfere, in 659; Ethelred, in 675, and Ceolred, in 709. Ethelwald, or Ethelbald, succeeded in 716; was designated the Proud; and alternately gained and lost large extension of territory. Offa the Terrible succeeded in 757; subdued parts of Kent and Sussex; wrested from Wessex all her territories on the left of the Thames; drove the Welsh beyond the Wye; constructed the rampart, known as Offa's dyke, from the Severn near Bristol to the mouth of the Dee, as a defence along the W boundary of his kingdom; pursued a course of conquest and victory through ten years; built a palace which was the wonder of the age, and struck coins and medals of a kind superior to any of that period; and completed his ambitions and warlike career by inflicting defeat on a body of Danes. Egfrid or Ecgfrith, Offa's son, succeeded in 785; Cenolf or Cynewulf, in 795; Kenelme, in 819; Burnwulf or Beoruwulf, in 821; and Viglaf, in 825. Egbert of Wessex made war against the last two of these kings; defeated Burnwulf in one battle in 823, and slew him in another in 825; achieved success also against Viglaf; and annexed all Mercia to Wessex in 828. Mercia n ever again figured as a kingdom; but it ranked at the Norman conquest as an earldom.

(John Marius Wilson, Imperial Gazetteer of England and Wales (1870-72))