Complex sentence: Rawdon was posted at Boston as a Lieutenant in the 5th Regiment of Foot's Grenadier company, during the Battles of Lexington and Concord, but he saw action at the Battle of Bunker Hill.
Split into simpler sentences: Rawdon was posted at Boston as a Lieutenant in the 5th Regiment of Foot's Grenadier company, during the Battles of Lexington and Concord. He first saw action at the Battle of Bunker Hill.