Battle of An Lộc The Battle of An Lộc was a major battle of the Vietnam War that lasted for 66 days and culminated in a decisive victory for South Vietnam . In many ways , the struggle for An Lộc in 1972 was an important battle of the war , as South Vietnamese forces halted the North Vietnam ese advance towards Saigon . Prelude . An Lộc is the capital of Bình Phước Province located northwest of Military Region III . During North Vietnam ' s " Easter Offensive " , officially known as the Nguyen Hue Offensive of 1972 , An Lộc was at the centre of North Vietnamese strategy due to its location on QL - 13 between Base Area 708 in Cambodia , and Saigon . To protect this important area the Republic of Vietnam had essentially one single division in Bình Phước Province , the ARVN 5th Division . During the battle the 5th ARVN division was outnumbered by a combined force of three North Vietnamese and Viet Cong divisions resulting in the most protracted conflict of the whole 1972 Easter Offensive . On the same day that Loc Ninh — a small town north of An Loc on the border with Cambodia was assaulted the ( NVA ) PAVN 7th division launched an attack on Route 13 in an attempt to cut off An Loc from Saigon . To control route QL - 13 was to control the road to Saigon , some to the south . This prevented resupply of ARVN forces in An Loc . Battle . On the 8 April 1972 the small town of Loc Ninh was overrun . About half of the defenders escaped to An Loc . This was the opening number in the concert of destruction that lay in wait for the defenders of An Loc . The siege of An Loc proper began with a 7 , 000 round a day artillery overture , reducing most of the town of An Loc to rubble . It is hard to overestimate the power of such a barrage , which counts as too heavy to even venture out of a bunker for a justified fear of imminent death . The defenders of An Loc were made up of several organizations of the 5th ARVN Division . They included the division ' s 8th Regiment with about 2 , 100 men ; the 7th Regiment which was short one battalion and only had 850 men ; the 9th Regiment , most of which was destroyed at Loc Ninh had only had 200 men ; Task Force 52 , 500 men ; the 3rd Ranger Group , 1 , 300 men ; as well as Binh Long Provincial Regional Force , Popular Forces , and People ' s Self - Defense Forces , about 2 , 000 men . The defenders were later reinforced by the elite 81st Airborne Commando Battalion and the 1st Airborne Brigade , brought in by air because QL - 13 was blocked by the NVA . The defenders also had little artillery and had to rely on US air support . Other reinforcements consisted of the 21st ARVN Division which was plagued by a very slow move from the Delta area in the south of the country and cleared QL - 13 after protracted fighting . The ARVN defenders did have one card to play throughout the battle , the immense power of US air support . The use of B - 52 Stratofortress bombers ( a strategic strike craft capable of carrying one hundred and eight MK82 ( 500 pound ) bombs on one run ) in a close support tactical role , as well as AC - 119 Stinger and AC - 130E Spectre gunships , fixed wing cargo aircraft of varying sizes , AH - 1 Cobra attack helicopters and Vietnamese Air Force ( VNAF ) A - 37 ' s . These methods worked to blunt the offensive from the North Vietnamese Army . At this stage in the war the NVA often attacked with PT - 76 amphibious and T - 54 medium tanks spearheading the advance , usually preceded by a massive artillery barrage . These tactics reflected Soviet doctrine , as the NVA had been supplied with Soviet ( and Chicom - Chinese Communist ) equipment ; including jets , artillery , and surface to air missiles since the beginning of the war . The battle eventually stagnated and became a periodic trade of artillery barrages , most probably as a result of casualties sustained in frustrated attacks on heavily entrenched enemy positions that could call in a withering array of supporting firepower . The first attack on the city occurred on April 13 . It was preceded by a powerful artillery barrage . The NVA captured several hills to the north and penetrated the northern portion of the city held by the 8th Regiment and 3rd Ranger Group . ARVN soldiers were not used to dealing with tanks , but early success with the M72 LAW , including by teen age members of the People ' s Self Defense Forces ( PSDF ) went a long way to helping them overcome their fear . The 5th Division commander , General Hung , later ordered tank - destroying teams be formed by each battalion , which included PSDF members who knew the local terrain and could help identify good locations to ambush tanks . They took advantage of the fact that the NVA forces , who were not used to working with tanks , often let the tanks get separated from their infantry by driving through ARVN defensive positions . At that point , all alone inside ARVN lines , they were vulnerable to the tank - destroying teams . The second attack on the city took place the next day , on April 15 . The NVA were concerned because the ARVN 1st Airborne Brigade had air - assaulted into positions west of the city and was coming to reinforce the defenders . Again the NVA preceded their attack with an artillery barrage followed by a tank - infantry attack . Again , their tanks became separated from their infantry and fell prey to ARVN tank - destroyer teams . NVA infantry following behind assaulted the ARVN defensive positions and pushed farther into the city . B - 52 strikes helped break up some NVA units assembling for the attack . By the afternoon of the 16th , fighting had died down . Unable to take the city , the North Vietnamese Army kept it under constant artillery fire . They also moved in more anti - aircraft guns to prevent aerial resupply . Heavy anti - aircraft fire kept Vietnamese Air Force ( VNAF ) helicopters from getting into the city after April 12 . Then fixed wing VNAF aircraft , C - 123 ' s and C - 119 ' s tried . Several were shot down and by April 19 the US Air Force took over . The US used C - 130 ' s to parachute in supplies , but many missed the defenders and aircraft were shot down or damaged . Low altitude drops during day and night did not do the job , so the USAF tried a new technique . On May 2 High Altitude Low Opening ( HALO ) techniques were tried . That method worked much better and was used until June 25 when the siege was lifted and aircraft could land at An Loc . Over the entire course of the resupply effort , the garrison recovered several thousand tons of supplies , the only supplies it received during the siege . On 11 May 1972 the North Vietnamese Army launched a massive all - out infantry and armor ( T - 54 medium tanks ) assault on the town . The attack was carried out by units of the 5th and 9th NVA divisions . This attack was repulsed by a combination of US airpower and the determined stand of ARVN soldiers on the ground . Almost every B - 52 in South East Asia was called in to strike the massing enemy tanks and infantry . The commander of the defending forces had placed a grid around the town creating many " boxes " each measuring 1 km by 3 km in size which were given a number and could be called by ground forces at any time , the B - 52 Arclight cells ( groups of 3 Aircraft ) were guided onto these boxes by ground based radar . During 11 and 12 May , the US Air Force managed an " Arc Light " mission every 55 minutes for 30 hours straight , using 170 B - 52 ' s and smashing whole regiments of NVA in the process . Despite that air support , the North Vietnamese made gains , and were within a few hundred meters of the ARVN 5th Division command post . ARVN counter - attacks were able to stabilize the situation . By the night of May 11 , the NVA consolidated their gains . On May 12 , they launched new attacks in an effort to take the city , but again failed . The NVA launched one more attack on May 19 in honor of Ho Chi Minh ' s birthday . The defenders were not surprised , and the attack was broken up by American air support and an ambush by the ARVN paratroopers . After the attacks of 11 and 12 May , the NVA directed its main efforts to cutting off any more relief columns . However , by the 9th of June this proved ineffective , and the defenders were able to receive the injection of manpower and supplies needed to sweep the surrounding area of North Vietnamese forces . By 18 June 1972 the battle had been declared over . Aftermath . The victory , however , was not complete , as Route 13 still was not open . The 18th ARVN division was moved in to replace the exhausted 5th Division . The 18th would spread out from An Loc and push the NVA back and the area stabilized . The fighting at An Lộc demonstrated the continued ARVN dependence on American air power and American advisors . For the NVA , it demonstrated their logistical constraints . They had to pause after each attack and bring up more supplies .