Duncan II (a.k.a. Donnchad mac Maíl Coluim) lived from 1060 to 12 November 1094 and was King of Scotland from Spring 1094 to 12 November 1094. The wider picture in Scotland at the time is set out in our Historical Timeline.
Duncan was the oldest son of Malcolm III by his first wife Ingibjörg. He had spent the 15 years following the signature of the Treaty of Abernethy in 1072 as a hostage in England against his father's good behaviour, before being released by William II in 1087.
If Scotland had been fully committed the principle of primogeniture at the time of the death of Malcolm III, his successor should have been Duncan II of Scotland, Malcolm's first son by his first marriage.
But Malcolm's brother Donald saw things differently. He had a vested interest in resurrecting the old process of tansitry, by which succession could be distributed more widely. He therefore took the crown for himself and ruled as Donald III, with support from Edmund, Malcom III's second son by Margaret.
In Spring 1094, Duncan came north into Scotland with the support of an English and Norman army and deposed his uncle and his step-brother, placing himself on the throne as Duncan II. But Duncan was seen as acting on behalf of William II and he received very little support within Scotland. The withdrawl of William's troops later in the year left Duncan very explosed, and he was murdered by the Mormaer of the Mearns on 12 November 1094, presumably under orders from Donald. After his murder, Donald III and Edmund resumed their joint reign.