Complex sentence: Shortly after leaving the university he served in Wolfe's regiment (20th Foot) during the Seven Years' War, and so distinguished himself at Minden and Kloster-Kampen that he was raised to the rank of Colonel.
Split into simpler sentences: Shortly after leaving the university he served in Wolfe's regiment (20th Foot) during the Seven Years' War. He so distinguished himself at Minden and Kloster-Kampen that he was raised to the rank of Colonel.