Vietman War - 1st Ca. Div., on patrol Lao Valley (operation "Pershing", 1967). Photo courtesy NARA. Unit's first major operation-Pleiku Campaign. The division conducted 35 days of continuous airmobile operations. The opening battle, Battle of Ia Drang Valley, was described in book "We Were Soldiers Once...And Young", also the basis of the subsequent Mel Gibson film "We Were Soldiers". The unit earned first Presidential Unit Citation (US) presented to a division during the Vietnam War.