Ecgfrith (died December 796) was a King of Mercia who briefly ruled in the year 796. He was the son and heir of King Offa of Mercia, and in 787, Offa had Ecgfrith crowned as co-ruler. He succeeded his father in July 796, but despite Offa's efforts to secure his son's succession, it is recorded that Ecgfrith ruled for only 141 days. Since Offa died either on July 26 or July 29, this would mean that Ecgfrith died either on December 14 or December 17. Events December - Coenwulf becomes king of Mercia. ... A list of the Kings etc. ... Mercia, sometimes spelled Mierce, was one of the kingdoms of the Anglo-Saxon heptarchy, in what is now England, in the region of the Midlands, with its heart in the valley of the River Trent and its tributary streams. ... Events December - Coenwulf becomes king of Mercia. ... Offa (died July 26/29, 796) was the King of Mercia from 757 until his death. ... This article is about the year 787. ... July 26 is the 207th day (208th in leap years) of the year in the Gregorian Calendar, with 158 days remaining. ... July 29 is the 210th day (211th in leap years) of the year in the Gregorian Calendar, with 155 days remaining. ... December 14 is the 348th day of the year (349th in leap years) in the Gregorian Calendar. ... December 17 is the 351st day of the year (352nd in leap years) in the Gregorian Calendar. ...