Complex sentence: From there the Italians ventured no further into Sudan owing to a lack of fuel and fortified Kassala with anti-tank defences, machine-gun posts and strongpoints, later establishing a brigade-strong garrison.
Split into simpler sentences: From there the Italians ventured no further into Sudan, owing to a lack of fuel. They proceeded to fortify Kassala with anti-tank defences, machine-gun posts and strongpoints, later establishing a brigade-strong garrison.