Complex sentence: He was also joined by the Earl of Sutherland and his small army from Clan Sutherland, as well as the Inverness commander Colonel Strachan, whose force was said to number about 230 cavalry, and a body of infantry.
Split into simpler sentences: He was also joined by the Earl of Sutherland and his small army from Clan Sutherland. Also in support of Leslie's army was the Inverness commander Colonel Strachan, whose force was said to number about 230 cavalry, and a body of infantry.