The Marines of CAP Oscar-3 and the Battle for Hill 689

Lance Corporal Francisco Albert Mazariegos was one of the Marines assigned to Combined Action Platoon Oscar-3 near Khe Sanh, Vietnam.

Unlike many Marines who served from larger bases, the men of the Combined Action Program lived among the villagers they were tasked with protecting. These small Marine teams worked alongside local Popular Force units, sharing daily life with the communities around them while providing security, training, and support.

Their mission was unlike any other in Vietnam. They were not simply defending a position behind sandbags and concertina wire. They were building relationships, earning trust, and fighting a war measured not by miles gained but by villages protected.

These Marines believed their presence mattered.

The Fight for Hill 689

On the morning of June 27, 1967, Lance Corporal Mazariegos joined a patrol from CAP Oscar-3 sent to investigate suspected North Vietnamese rocket and mortar positions. These enemy positions had been responsible for attacks against the Khe Sanh combat base during the previous night.

The patrol moved toward Hill 689, a rugged position overlooking the surrounding area.

There, they discovered far more than they expected.

The Marines and their Bru Popular Force allies encountered a heavily fortified North Vietnamese force waiting in prepared positions. The patrol was caught in a devastating ambush, and intense enemy fire quickly turned the hillside into a desperate fight for survival.

As the Marines attempted to evacuate their wounded and recover their fallen, the enemy continued to strike. Efforts by nearby Combined Action units to reach the trapped patrol were pushed back by heavy fire. Marines from the 3rd Battalion, 26th Marines also suffered additional casualties while attempting to break through and assist their fellow Marines.

For days, the battle continued as artillery and air strikes hammered the enemy positions on Hill 689. Eventually, the North Vietnamese defenses were overcome, but the cost had already been paid.

Among those who never came down from the hill was Lance Corporal Francisco Albert Mazariegos.

Remembering CAP Oscar-3

The Marines of the Combined Action Program served a unique role in the Vietnam War. Often young and far from major bases, they lived in remote villages, sharing hardships with the local people and standing alongside their Popular Force counterparts.

Their battlefield was personal. Their victories were measured in the lives they protected and the bonds they formed. Their dangers often came without warning, on isolated patrols far from immediate support.

On Hill 689, Lance Corporal Mazariegos made the ultimate sacrifice alongside his fellow Marines and the Vietnamese allies who fought beside them.

Today, we remember Lance Corporal Francisco Albert Mazariegos, a Marine of Combined Action Platoon Oscar-3, and all those who served in the difficult and often overlooked missions of the Combined Action Program.

Semper Fidelis.