Question: which battle took place first,  Battle of Belleau Wood or Operation Diadem ?
Sentence (from "Battle of Suoi Chau Pha"): Following a covert insertion the day before which had caught a number of Viet Cong sentries by surprise, A Company, 7th Battalion, Royal Australian Regiment (7 RAR) had patrolled forward unaware of the presence of a large Viet Cong main force unit nearby.
Relevant evidence: No