Complex sentence: For the next four years he served on various ships and shore stations and in June 1913 was promoted to Bombardier and this was soon followed by further rises to Corporal in 1915 and Sergeant in 1917.
Split into simpler sentences: For the next four years he served on various ships and shore stations and in June 1913 was promoted to bombardier. This was soon followed by further rises to corporal in 1915 and sergeant in 1917.