On March 13, 1954, the Battle of Dien Bien Phu of the First Indochina War begins in northern Vietnam as Viet Minh forces launch their assault on the French forces in the valley. The French, believing that establishing a heavily fortified position along the Viet Minh's supply lines would lure them out to be destroyed, had airlifted upwards of 16,000 men as well as multiple M24 Chaffee tanks and multiple aircraft into the area and established a secure airfield and a series of fortified outposts. On March 13, the first of these outposts, known as Beatrice, was attacked by Viet Minh forces. Utilizing direct-fire from artillery pieces brought into the area despite the difficult terrain, the Viet Minh forces successfully captured the outpost early in the morning of March 14. By early morning on March 17, a further outpost, Gabrielle, had been eliminated and another, Anne-Marie, was abandoned by the local Tai troops defending it following a propaganda campaign conducted by the Viet Minh saying this wasn't their fight and the loss of the other two outposts. Furthermore, the airstrip had been rendered unusable and thus the French were forced to deliver supplies by parachute. From March 17 to March 30, there was a lull in the fighting during which struggles over command among the French emerged while the Viet Minh forces solidified their position and inflicted heavy losses on French air assets by using anti-aircraft weaponry the French had not expected the Viet Minh to be able to field.
From March 30 to April 5, Viet Minh forces renewed their assaults against the remaining French positions; however, high casualty rates soon saw the battle devolve into trench warfare. Over the next month, both sides suffered heavy losses while the Viet Minh made incremental gains. On May 1, the Viet Minh once more renewed a major assault. Only ~3,000 French and colonial troops were left defending their positions against ~25,000 Viet Minh troops when the final assault began on May 7. By 6:20 that afternoon, only one French strongpoint, defended by Moroccan troops, still stood. This position soon fell later that night as the defenders surrendered following the destruction of the entirety of the remaining French forces at Dien Bien Phu. The battle had concluded in a decisive victory for the Viet Minh. French casualties included upwards of 2,300 killed, upwards of 6,600 wounded, 1,700 missing, and over 11,700 captured. Viet Minh casualties totaled ~4,000 dead, ~9,100 wounded, and nearly 800 missing. For the French, the losses were devastating and heavily contributed to the French withdrawal from the war and the region. The Viet Minh victory also influence the outcome of the Geneva Conventions and the partition of Vietnam which would also set the stage for the later American involvement in the country and ultimately the Vietnam War.