Complex sentence: He first experienced military life during the French and Indian War as a Captain of a local militia in 1760, and continued serving in the British military until the start of the revolution in 1775, in which he enlisted in the Continental Army as a Colonel.
Split into simpler sentences: He first experienced military life during the French and Indian War as a Captain of a local militia in 1760. He continued serving in the British military until the start of the revolution in 1775, in which he enlisted in the Continental Army as a Colonel.