Edward pursued an aggressive and generally successful policy in dealing with Scotland and Wales. Malcolm Canmore was an exile at Edward's court after his father, Duncan I, was killed in battle in 1040, against men led by Macbeth who seized the Scottish throne. In 1054, Edward sent Siward to invade Scotland. He defeated Macbeth, and Malcolm, who had accompanied the expedition, gained control of southern Scotland. By 1058, Malcolm had killed Macbeth in battle and had taken the Scottish throne. In 1059, he visited Edward, but in 1061, he started raiding Northumbria with the aim of adding it to his territory. In 1053, Edward ordered the assassination of the south Welsh prince Rhys ap Rhydderch in reprisal for a raid on England, and Rhys's head was delivered to him. In 1055, Gruffydd ap Llywelyn established himself as the ruler of Wales, and allied himself with Ælfgar of Mercia, who had been outlawed for treason. They defeated Earl Ralph at Hereford, and Harold had to collect forces from nearly all of England to drive the invaders back into Wales. Peace was concluded with the reinstatement of Ælfgar, who was able to succeed as Earl of Mercia on his father's death in 1057. Gruffydd swore an oath to be a faithful under-king of Edward. Ælfgar likely died in 1062, and his young son Edwin was allowed to succeed as Earl of Mercia, but Harold then launched a surprise attack on Gruffydd. He escaped, but when Harold and Tostig attacked again the following year, he retreated and was killed by Welsh enemies. Edward and Harold were then able to impose vassalage on some Welsh princes. In October 1065, Harold's brother, Tostig, Earl of Northumbria, was hunting with the king when his thegns in Northumbria rebelled against his rule, which they claimed was oppressive, and killed some 200 of his followers. They nominated Morcar, the brother of Edwin of Mercia, as earl and invited the brothers to join them in marching south. They met Harold at Northampton, and Tostig accused Harold before the king of conspiring with the rebels. Tostig seems to have been a favourite with the king and queen, who demanded that the revolt be suppressed, but neither Harold nor anyone else would fight to support Tostig. Edward was forced to submit to his banishment, and the humiliation may have caused a series of strokes which led to his death. He was