Battle of Mang Yang Pass The Battle of Mang Yang Pass ( also known as Battle of An Khe ) was the last official battle of the First Indochina War . It was one of the bloodiest defeats of the French Union together with the battle of Dien Bien Phu in 1954 and the battle of Cao Bang in 1950 . Background . " Groupement Mobile No . 100 " ( " Mobile Group 100 " or G . M . 100 ) was a regimental task force unit of the French Far East Expeditionary Corps which was assembled as a convoy . It included the elite veteran UN " Bataillon de Corée " who fought in the Korean War at Chipyong - ni , Wonju and Arrowhead Ridge . Anxious to avoid a second disaster like the siege at Dien Bien Phu , the French Chief of Staff ordered G . M . 100 to abandon their isolated position in the Central Highlands . Ambushes . On June 24 , 1954 , G . M . 100 received orders to abandon its defensive positions at An Khe and fall back to Pleiku , some 80 kilometers away over Route Coloniale 19 . At the road marker ' Kilometer 15 ' the column was ambushed by Viet Minh troops belonging to the 803rd Regiment and suffered heavy losses . The remains of G . M . 100 managed to break through the ambush . The remnants of G . M . 100 , now with G . M . 42 and the 1st Airborne Group had to brave 55 kilometers more of enemy road and was ambushed on June 28 and 29 at Dak Ya - Ayun by the Viet Minh 108th Regiment . The survivors finally reached Pleiku the following day . In five days of fighting , G . M . 100 lost 85 percent of vehicles , 100 percent of artillery , 68 percent of signal equipment and 50 percent of weapons . The Headquarters Company had only 84 men left out of an original 222 . The 43rd Colonial , the 1st and the 2nd Korea Battalion which numbered about 834 men each , was now mustered at roll call with 452 , 497 , and 345 men respectively . The 2nd Group of the 10th Colonial Artillery , reduced to fighting as infantry after the loss of all of their guns , had shrunk from 475 men to 215 men during the fighting . Colonel Barrou and several men were taken as prisoners of war . The Viet Minh 96th Regiment suffered more than 100 KIAs in comparison . On June 29 , the remains of 1st Korean Battalion was ordered to take part in Operation Forget - Me - Not to open Route Coloniale 14 between Pleiku and Ban Me Thuot which was over 96 kilometers away . On July 17 , the column was ambushed at Chu Dreh Pass by local units of the Viet Minh 96th Regiment . When the survivors finally arrived at Ban Me Thuot the following day , there were only 107 men remaining out of 452 , of those 53 were wounded , in addition a further 47 vehicles were lost . Aftermath . The ambush and destruction of GM 100 was considered the last battle of the First Indochina War . Three days later on July 20 , 1954 , a battlefield ceasefire was announced , and on August 1 , the armistice went into effect , sealing the end of the French Indochina and soon the departure of the French administration and Expeditionary Corps which was completed by 1956 . Order of battle . French Forces . The G . M . s ( Groupement Mobile ) were designed as self - sustaining motorized regimental task force unit modeled after the U . S . Army ’ s World War II regimental combat team s . The G . M . s typically consisted of three infantry battalions with one artillery battalion , along with elements of light armor or tanks , engineer , signal and medical assets , totaling 3 , 000 - 3 , 500 soldiers . Units in the G . M . 100 included : Viet Minh forces . The Viet Minh 96th Regiment included : In popular culture . The destruction of Groupement Mobile 100 is depicted in the opening scene of " We Were Soldiers " .