Kent. Another king of Kent, Ecgberht, appears on a charter in 765 along with Heahberht; the charter was subsequently confirmed by Offa. Offa's influence in Kent at this time is clear, and it has been suggested that Heahberht was installed by Offa as his client. There is less agreement among historians on whether Offa had general overlordship of Kent thereafter. He is known to have revoked a charter of Ecgberht's on the grounds that "it was wrong that his thegn should have presumed to give land allotted to him by his lord into the power of another without his witness", but the date of Ecgberht's original grant is unknown, as is the date of Offa's revocation of it. It may be that Offa was the effective overlord of Kent from 764 until at least 776. The limited evidence for Offa's direct involvement in the kingdom between 765 and 776 includes two charters of 774 in which he grants land in Kent; but there are doubts about their authenticity, so Offa's intervention in Kent prior to 776 may have been limited to the years 764–65. The Anglo-Saxon Chronicle records that "the Mercians and the inhabitants of Kent fought at Otford" in 776, but does not give the outcome of the battle. It has traditionally been interpreted as a Mercian victory, but there is no evidence for Offa's authority over Kent until 785: a charter from 784 mentions only a Kentish king named Ealhmund, which may indicate that the Mercians were in fact defeated at Otford. The cause of the conflict is also unknown: if Offa was ruling Kent before 776, the battle of Otford was probably a rebellion against Mercian control. However, Ealhmund does not appear again in the historical record, and a sequence of charters by Offa from the years 785–89 makes his authority clear. During these years he treated Kent "as an ordinary province of the Mercian kingdom", and his actions have been seen as going beyond the normal relation of overlordship and extending to the annexation of Kent and the elimination of a local royal line. After 785, in the words of one historian, "Offa was the rival, not the overlord, of Kentish kings". Mercian control lasted until 796, the year of Offa's death, when Eadberht Præn was temporarily successful in regaining Kentish independence. Ealhmund was probably the father of Egbert of Wessex, and it is possible that