Complex sentence: Following the conclusion of the Raid of Ruthven in 1582, the Earl of Arran took effective control of Scotland, and used his power to pursue his enemies, namely Gowrie and his supporters.
Split into simpler sentences: Following the conclusion of the Raid of Ruthven in 1582, the Earl of Arran took effective control of Scotland. Arran used his power to pursue his enemies, namely Gowrie and his supporters.