 However, it is known that when Egbert of Wessex and his son Æthelwulf invaded Kent in 825 they put Baldred to flight and imposed their own rule.Egbert's campaign of conquest took him far beyond Kent and even through Mercia to the borders of Northumbria in 829–30.Unusually, this dramatic military success was reflected in an issue of coinage from London, with Egbert named REX M("erciorum").