Duncan invades in May 1094 at the…

Duncan invades in May 1094 at the head of an army of Anglo-Normans and Northumbrians, aided by his half-brother Edmund and his father-in-law Gospatric, Earl of Northumbria.

This invasion succeeds in placing Duncan on the throne as Duncan II, but an uprising defeats his allies and he is compelled to send away his foreign troops.

Duncan is then killed on November 12, 1094 by Máel Petair, Mormaer of Mearns, a supporter of Donald III.

The Annals of Ulster say that Duncan was killed on the orders of Donald (incorrectly called his brother) and Edmund.

Donald resumes power, probably with Edmund as his designated heir.

Donald is an elderly man by the standards of the day, approaching sixty years old, and without any known sons, so that an heir is clearly required.

William of Malmesbury says that Edmund bargained "for half the kingdom", suggesting that Donald granted his nephew an appanage to rule.