Malcolm was a prince of great abilities and prudence, and Edmund I of England courted his alliance by ceding Cumbria, the consisting of Cumberland and part of Westmorland, to him, in the year 945, on condition that he would defend that northern county, and become an ally of Edmund. This, therefore, required Scotland to send military support if England was attacked by either the Danes of Northumbria or the Norwegians of Ireland. The alliance between England and Scotland remained after the death of both kings.
Edred of England, the brother and successor of Edmund, accordingly applied for, and obtained, the aid of Malcolm against Anlaf, king of Northumberland, whose country, according to the barbarous practice of the times, he wasted, and carried off the people with their cattle.
Later, when Norsemen again invaded the land, the Scots sent raids against the English and, in 954, Edred reunited the northern counties to his dominions.
In this same year, after putting down an insurrection of the Moray-men under Cellach, their Maormor (chief), whom he killed, Malcolm was slain, probably at Ulurn or Auldearn in Moray, by one of these men, in revenge for the death of his chief. He was buried on the Isle of Iona.
At some point in his life, he married. But as was the case with many monarchs in this period, the details are no longer known. A son from this marriage would later succeed to the throne as Kenneth II of Scotland.
| Preceded by: Constantine II |
List of British monarchs | Succeeded by: Indulf |