Complex sentence: At his death in 1936 aged 97 he was the last surviving soldier of the 57th Regiment that had fought in the New Zealand Wars; he may have been the war's last surviving combatant but this is impossible to confirm due to incomplete records.
Split into simpler sentences: At his death in 1936 aged 97 he was the last surviving soldier of the 57th Regiment that had fought in the New Zealand Wars. He may have been the war's last surviving combatant but this is impossible to confirm due to incomplete records.