Complex sentence: Lt.-Col. Robert Chichester gained the rank of Major in the service of the Irish Guards and served in the British Central Africa Campaign (1897--1900), later gaining the rank of Lieutenant-Colonel in the service of the Royal Irish Rifles.
Split into simpler sentences: Lt.-Col. Robert Chichester gained the rank of Major in the service of the Irish Guards and served in the British Central Africa Campaign between 1897 and 1900. He gained the rank of Lieutenant-Colonel in the service of the Royal Irish Rifles.