Complex sentence: Intensive conversion training to becoming an Armoured unit was carried out, whilst in May part of the regiment went up to the desert, taking part in the Battle of Gazala by holding the defensive box called "Knightsbridge".
Split into simpler sentences: Intensive conversion training to becoming an Armoured unit was carried out. In May, part of the regiment went up to the desert, taking part in the Battle of Gazala by holding the defensive box called "Knightsbridge".