Complex sentence: During an attack on the fortification at Thiaumont, Verdun, on 23 June 1916, he sustained a serious chest wound and spent the remainder of the war in France and Romania as a staff officer.
Split into simpler sentences: During an attack on the fortification at Thiaumont, Verdun, on 23 June 1916, he sustained a serious chest wound. As a result, he spent the remainder of the war in both France and Romania as a staff officer.