It was only now, with the independence of Wessex hanging by a thread, that Alfred emerged as a great king. In May 878 he led a force that defeated the Danes at Edington. The victory was so complete that the Danish leader, Guthrum, was forced to accept Christian baptism and withdraw from Mercia. Alfred then set about strengthening the defences of Wessex, building a new navy—60 vessels strong. Alfred's success bought Wessex and Mercia years of peace and sparked economic recovery in previously ravaged areas.