Complex sentence: In February 1941, Mussert agreed and oversaw the formation of the 23rd SS Volunteer "Panzer Grenadier" Division "Nederland", which after training in Hamburg served with honour on the Eastern front alongside their Nazi allies, but suffered large losses.
Split into simpler sentences: In February 1941, Mussert agreed and oversaw the formation of the 23rd SS Volunteer "Panzer Grenadier" Division "Nederland", which trained in Hamburg. It served with honour on the Eastern front alongside their Nazi allies, but suffered large losses.