Complex sentence: He continued serving after the war with his regiment, when it became 24 (Derbyshire Yeomanry) Armoured Car Company of the Royal Tank Regiment in 1923, was promoted Major in 1932, and became Lieutenant Colonel in command in 1935.
Split into simpler sentences: He continued serving after the war with his regiment, which became 24 (Derbyshire Yeomanry) Armoured Car Company of the Royal Tank Regiment in 1923. He was promoted Major in 1932, and became Lieutenant Colonel in command in 1935.