In the summer of 1015, Canute's fleet set sail for England with a Danish army of perhaps 10,000 in 200 longships. Cnut was at the head of an array of Vikings from all over Scandinavia. The invasion force was to be in often close and grisly warfare with the English for the next fourteen months. Practically all of the battles were fought against Aethelred's son, Edmund Ironside.