Complex sentence: In the Western Offensive he fought under Field Marshal Fedor von Bock and commanded the 18th Army, which invaded the Netherlands, participating in the fighting at Moerdijk, Rotterdam, and the Hague.
Split into simpler sentences: In the Western Offensive he fought under Field Marshal Fedor von Bock. His 18th Army invaded the Netherlands, participating in the fighting at Moerdijk, Rotterdam, and the Hague.