Complex sentence: Crown Prince Alexander graduated from the Royal Military Academy Sandhurst in 1966 and was commissioned as an officer into the British Army's 16th/5th The Queen's Royal Lancers regiment, rising to the rank of captain.
Split into simpler sentences: Crown Prince Alexander graduated from the British Royal Military Academy and in 1966 was commissioned an officer in the British Army. He served in the 16th/5th The Queen's Royal Lancers rising to the rank of captain.