Malcolm I (A.K.A Máel Coluim mac Domnaill) became king of Scots when his cousin Constantine II (A.K.A Causantín mac Áeda) abdicated to become a monk. He was the son of Donald II (A.K.A Domnall mac Causantín). It was Constantine who left the throne to Malcolm.
Malcolm was not a young man when he eventually took the throne. His father had died in 900AD so he would have been born no later than 901AD, this would have put him comfortably in his 40s or even 50s when he became King. He must have been very impatient waiting for his time to come or like is talked about in the 11th-century Prophecy of Berchán, a verse history in the form of a supposed prophecy, states that his decision was not a voluntary one. Later (around 7 years) the Chronicle of the Kings of Alba says:
“[Malcolm I] plundered the English as far as the River Tees, and he seized a multitude of people and many herds of cattle: and the Scots called this the raid of Albidosorum, that is, Nainndisi. But others say that Constantine made this raid, asking of the king, Malcolm, that the kingship should be given to him for a week’s time, so that he could visit the English. In fact, it was Malcolm who made the raid, but Constantine incited him, as I have said.”
We do not know if this was true and the raid could have been a late addition to the chronicle and more based on a now lost saga or poem.
In 945 Edmund of Wessex, having expelled Amlaíb Cuaran (Olaf Sihtricsson) from Northumbria, devastated Cumbria and blinded two sons of Domnall mac Eógain, king of Strathclyde. It is said that he then “let” or “commended” Strathclyde to Malcolm in return for an alliance.
Malcolm appears to have kept his agreement with the late English king, which may have been renewed with the new king, Edmund having been murdered in 946 and succeeded by his brother Edred. Eric Bloodaxe took York in 948, before being driven out by Edred, and when Amlaíb Cuaran again took York in 949–950, Malcolm raided Northumbria as far south as the Tees taking “a multitude of people and many herds of cattle” according to the Chronicle.
Sagas tell of King Malcolm making war with the Kingdom of Moray and notably slaying the great warrior Cellach in 949.
The Annals of Ulster for 952 report a battle between “the men of Alba and the Britons [of Strathclyde] and the English” against the foreigners, i.e. the Northmen or the Norse-Gaels. This battle is not reported by the Anglo-Saxon Chronicle, and it is unclear whether it should be related to the expulsion of Amlaíb Cuaran from York or the return of Eric Bloodaxe.
The Annals of Ulster report that Malcolm was killed in 954. Other sources place this most probably in the Mearns, either at Fetteresso following the Chronicle, or at Dunnottar following the Prophecy of Berchán. In sagas Malcolm is slain at Mearns in 954 AD by the Mormaer of Angus and Mearns, Cosgrach the Wolfslayer.
He was buried on Iona. Malcolm’s sons Dub and Cináed were later kings, next to his father and grandfather King Constantine II in the MacAlpin mausoleum.