Complex sentence: The Clan Sutherland and Clan Murray led by Hutcheon Murray of Abirscors with Gilbert Gordon of Garty decided to attack the Mackays at a place called Ailtan-Beath.
Split into simpler sentences: The Clan Sutherland and Clan Murray led by Hutcheon Murray of Abirscors with Gilbert Gordon of Garty decided to attack the MacKays. They attacked the MacKays at a place called Ailtan-Beath.