Complex sentence: As part of this formation, the regiment fought at the Siege of Tunis in May 1943 and then landed in Naples in January 1944, before taking part in the Battle of Monte Cassino in May 1944.
Split into simpler sentences: As part of this formation, the regiment fought at the Siege of Tunis in May 1943 and then landed in Naples in January 1944. It saw action at the Battle of Monte Cassino in May 1944.