Complex sentence: In 1944, the Polish forces in the West were making a substantial contribution to the war: in May, participating in the Italian Campaign, the Second Corps under General Anders stormed the fortress of Monte Cassino and opened a road to Rome.
Split into simpler sentences: In 1944, the Polish forces in the West were making a substantial contribution to the war. In May, participating in the Italian Campaign, the Second Corps under General Anders stormed the fortress of Monte Cassino and opened a road to Rome.