Complex sentence: Many Gurkha volunteers served in non-combatant roles, serving in units such as the Army Bearer Corps and the labour battalions, but there were also large numbers that served in combat in France, Turkey, Palestine, and Mesopotamia.
Split into simpler sentences: Many Gurkha volunteers served in non-combatant roles, serving in units such as the Army Bearer Corps and the labour battalions. Also, a large number served in combat in France, Turkey, Palestine, and Mesopotamia.