Offa of Mercia 

He was a devout Christian, a contemporary of Charlemagne, and founded the archdiocese of Lichfield with the approval of Pope Adrian I. His power spread over such a large part of England, that he prided himself to be the King of England; he was the only king of Western Europe to be regarded as an equal by Charlemagne. He introduced silver coinage in England, producing the first English silver pennies, as well as a copy of the gold dinar of the Abassid[?] caliph Al-Mansur dated 157AH, which differs from the original by adding the inscription OFFA REX. Since this coin contains the Arabic profession of faith in Allah, it has been cited by some as proof that Offa had converted to Islam. However, it is infinitely more likely that the coin was produced in order to trade with Islamic Spain, and the king, his engravers, and officials, simply copied the Arabic coin without any comprehension of what the inscriptions said (particularly since "OFFA REX" is upside down in relation to the Arabic script, and the word "year" is misspelled in Arabic).

Following the murder of his cousin, King Æthelbald in 757, Offa defeated and exiled Beornrad[?], Æthelbald's successor, thus seizing the throne of Mercia. A series of campaigns against the Kentish Saxons led eventually to the decisive Battle of Otford[?] in 775. The Battle of Bensington[?] in Oxfordshire ended the power of the West Saxons.

He is perhaps best known for Offa's Dyke, a great earthen wall between England and Wales. However, although this landmark is named after Offa, it isn't known with certainty to what extent he was responsible for its construction. Some attribute the building of all or parts of the dyke to earlier periods.

Sir Frank M. Stenton[?] in his authoritative history, Anglo-Saxon England, believed that Offa was perhaps the greatest king of the Anglo-Saxon kingdoms, the proof of his ability obscured by the lack of a historian to describe his achievements. "No other Anglo-Saxon king ever regarded the world at large with so secular a mind or so acute a political sense," writes Sir Frank.

Offa died July 26, 796. He had exerted himself to secure that his son Ecgfrith would succeed him, but Ecgfrith was able to hold onto the throne for only five months. After his death, Mercia fell into decline. Only a quarter of a century after his death (825), the role of leading English power passed to Wessex.