Complex sentence: As a young officer in the Bourbon Royal army, he served in the Seven Years'War, and in the American Revolutionary War he joined Rochambeau's "Expédition Particulière" (Special Expedition) supporting the American colonists.
Split into simpler sentences: As a young officer in the Bourbon Royal army, he served in the Seven Years'War. In the American Revolutionary War he joined Rochambeau's "Expédition Particulière" (Special Expedition) supporting the American colonists.