Complex sentence: O'Connor's remit was to engage in aggressive patrolling along the frontier and he set out to dominate no-man's land by creating "jock columns," mobile formations based on units of 7th Armoured Division, which combined tank, infantry and artillery.
Split into simpler sentences: O'Connor's remit was to engage in aggressive patrolling along the frontier. He set out to dominate no-man's land by creating "jock columns," mobile formations based on units of 7th Armoured Division, which combined tanks, infantry and artillery.