There were three important bases 21km to the north-east of Saigon: ARVN III Corps headquarters in Bien Hoa; the United States Air Force base on the outskirts of Bien Hoa; and the huge ammunition dump at Long Binh. Following General Westmoreland’s cancellation of the ceasefire, 9th Division’s 2/47th Infantry (Mechanised) had set up blocking positions around all three. By 5.00am on 31 January, all three bases reported that they were under attack by units of the 5th VC Division. Lieutenant Colonel John B. Tower deployed his three mechanised companies to relieve the garrisons in what would become a confusing number of skirmishes all across the Bien Hoa–Long Binh area.
Company A engaged 275th VC Regiment in Ho Nai village before relieving the garrison of the nearby prisoner-of-war compound on Route 1. Company B made its way to Long Binh ammunition dump, driving out the Viet Cong sappers before they could detonate their satchel charges. Meanwhile, Company C fought its way past 275th VC Regiment astride Highway 1 before stopping 274th VC Regiment’s attack on Bien Hoa airbase. It went on to infiltrate Bien Hoa town, breaking up 238th VC Battalion’s siege of III Corps’ compound. Company C spent the rest of the day engaged in house-to-house fighting and, by nightfall, it had cleared Bien Hoa after having only suffered eight casualties.
While Colonel Tower’s men worked their way towards Bien Hoa town, Troop A from 9th Division’s 3rd Squadron, 5th Cavalry, drove down Highway 1 towards Bien Hoa airbase. They had to brave the same corridor of fire on the long journey, returning fire as they drove through an ambush in Trang Bom. Although a destroyed bridge stopped most of the tanks reaching their objective, the M113s forded the stream. They reinforced 2/506th Battalion, 101st Airborne Division, which had been fighting since it had been airlifted into the base earlier that morning.
The Viet Cong had wanted to halt planes and helicopters taking off from the airfield, stopping them providing fire support to units around Saigon. However, the plan to storm the main gate and overrun the helicopter area never materialised. Elsewhere on the base, the Viet Cong tried in vain to storm the bunkers, aiming to turn their heavy machine-guns on the runways. Instead, helicopter gunships helped the troops on the ground clear the east end of the base by nightfall. The battle continued the following day, but the Viet Cong finally disengaged when 11th Armored Cavalry Regiment arrived at dusk. After a difficult thirty-six hours, Bien Hoa airbase was fully operational again.
At first light on 1 February, 1st Infantry Division assembled reaction forces at its bases north of Saigon and were soon heading south along Route 1. The Big Red One was expecting trouble and, when Major General John H. Hay’s infantry ran into 273rd VC Regiment’s roadblocks, they surrounded Phu Loi while their artillery deployed. For once, the Viet Cong were not going to escape into the jungle and after the howitzers had fired 3,500 rounds at the village, the GIs moved in to mop up the survivors. There were not many; 273rd Regiment had been decimated, leaving the main road to Saigon open.