Complex sentence: In 1911 Leighton met a young music hall manager Frederick Charles Cockerill (1882--1953); at the start of the 1914-18 War Cockerill received a commission in the Artists' Rifles and in 1915 Leighton and Cockerill married.
Split into simpler sentences: In 1911 Leighton met a young music hall manager Frederick Charles Cockerill. At the start of the 1914-18 War Cockerill received a commission in the Artists' Rifles and in 1915 Leighton and Cockerill married.