Murder at Dingwall

from wikipedia:

In 1370 a feud arose between William de Moravia, 5th Earl of Sutherland (chief of Clan Sutherland) and Aodh Mackay (chief of Clan Mackay). A meeting was arranged for them to meet at Dingwall Castle to resolve their issues. However Aodh Mackay and his son Donald Mackay were both murdered in the castle while they were asleep by Nicholas Sutherland, brother of the Earl of Sutherland.

1371 - Murder of two Mackay chieftains, father and son, at Dingwall Castle by Nicholas Sutherland of Duffus, head of one of the junior branches of Clan Sutherland. Much bloodshed followed, including a retaliatory raid on Dornoch in 1372. The cathedral was once again set on fire and many Sutherland men were hanged in the town square. After this, the feud quietened down as both sides were called away to fight against the English.

Raid of Dornoch 1372; The habitual enemies of Clan Sutherland were the Clan Sinclair of Caithness, Clan MacKay and the Clan McLeod to the west of Sutherland. The long dispute with the MacKays came to a head when Nicholas Sutherland of Duffus, head of one of the junior branches, murdered Mackay and his heir in their beds at Dingwall Castle where they had met in an attempt to patch up the feud. Much bloodshed followed, including a retaliatory raid on Dornoch. The cathedral was once again set on fire and many Sutherland men were hanged in the town square. After this, the feud quieted down as both sides were called away to fight against the English.

from clansutherland.org:

The long dispute with the MacKays first came to a head in 1372, when Nicholas Sutherland of Duffus, head of one of the junior branches, murdered Mackay and his heir in their beds at Dingwold Castle where they had met in an attempt to patch up the feud. Much bloodshed followed, including a retaliatory raid on Dornoch. The cathedral was once again set on fire and many Sutherland men were hanged in the town square. After this, the feud quieted down as both sides were called away to fight against the English.

from "...Earldom":
Sir Robert Gordon again seems to confuse people, and has Nicolas Southerland listed as an Earl of Southerland, even though he never was. Gordon seems to have added in a few Earls, getting confused over who were the sons of William, the 5th Earl of Sutherland. However, Gordon does include an account of the murder at Dingwall, which we know from several sources to have been committed by Nicholas Sutherland of Duffus.
"Haveing met ther at the appoynted tyme, they lodged both in the castle of Dingwall in severall chambers hard by one another. Earle Nicholas and Y-Macky fell at some hott reasoning and altercation anent these particulars then in controversie betueine them, and being incensed in anger one against another, upon the repetition of by past injuries, with some reproachfull words, he killed Y-Macky and his sone Donald with his owne hands, and hardlie escaping from ther followers and servants, he returned home with all speid into Southerland, the yeir of God 1395." (p. 58)