Since early February 1969, U.S. reconnaissance detected that 3 People's Army of Vietnam (PAVN) Regiments, the 27th, 138th and 246th were moving south from the Vietnamese Demilitarized Zone (DMZ).

With bad weather limiting air support the Marines dug in and were subjected to small arms and mortar fire.

On the afternoon of 5 March following an artillery barrage the Marines assaulted the summit of Mack clearing numerous PAVN bunkers.

[1]: 53 On 9 March Company G 2/4 Marines moved to reopen Landing Zone Catapult 4 km north of Firebase Neville overlooking the Cam Lộ valley.

[1]: 56 On 10 April Company E 2/5 Marines assaulted a PAVN bunker and cave complex in the Cam Lộ valley capturing several prisoners and stocks of weapons and ammunition.