Indochina is the name for 3 country's that initially came under French rule in the 1800's, namely Laos, Cambodia and Vietnam. Although the French brought architecture, railways and roads they also ruled the region with an iron fist, any insurrection being harshly subdued, as has been the way of all empire builders since the beginning of time.
French hegemony was interrupted during WW2 by the Japanese who annexed the country once France had been defeated by Germany. After the Japanese defeat in 1945, the French were keen to reestablish their control over Indochina and carry on with the rule of French law as if nothing had changed during the interim. Unfortunately for the French, the seeds of independence had been fermented by the Viet Minh, a Communist group of revolutionaries led by Ho Chi Minh. Although initially not very successful, the rise of China as a Communist power in 1949 led to a large increase in weapons for the Viet Minh. With more and more heavy weapons being supplied to them, the Viet Minh grew in confidence and were able to take on the French in set piece battles and by using guerilla warfare tactics to subdue any smalltime opposition be it civil or military. The Viet Minh had grown to such a size that they were deploying fully fledged combat division formations in the field by this stage of the war.
The Viet Minh were as brutal if not more so than the French, any civilian who showed any disobedience to their cause would be swiftly dispatched by machete, firing squad or sometimes buried alive. Thousands of innocent people died under their regime even before it became the official governing body of the country. On the battlefield the Viet Minh leadership showed little regard for their soldiers welfare and favoured mass wave attacks by infantry against French positions, with a horrendous loss of life that has still not been made official to this day. They were more successful in ambushing French convoys and vast swathes of the country were no go areas for the authorities, as the Communists tightened their grip.
After 8 years it was acknowledged that this was now a fully fledged war, the French decided on a set piece battle that would destroy the Viet Minh once and for all, luring them to a place called Dien Bien Phu (DBP). The operation was codenamed Operation Castor.
Parachuting men and equipment into DBP in November 1953 the French set up a heavily defensible position surrounded by mountains. As there was an airfield there, artillery and tanks were also transported via this method into the camp.
The French rightly assumed assumed the Viet Minh would come en masse to expel the French, they wrongly assumed the Viet Minh would not be able to bring heavy artillery to bear onto the forward facing slopes overlooking the camp. By a mammoth effort using thousands of Viet Minh soldiers and civilians they succeeded in bringing artillery fire to bear onto the French positions by March 1954 . Within two months and after a daily artillery barrage and a seemingly unending appetite for sending infantry in suicidal assaults against heavily fortified positions, the Viet Minh succeeded in overrunning DBP.
The 11,000 French army survivors were marched off into captivity where over 70% of the French died during a 3 month period of captivity, the Vietnamese/Thai/Cambodian allies of the French who were interned at the same time suffered over 90% death rate in the camps, basically they were starved to death. Interestingly Dien Bien Phu has often be called the last stand of the SS, the ranks of the legion being filled at that time with many Germans from Hitler's 3rd Reich.
The war ended shortly after DBP with the French agreeing to leave Indochina and an interim government being set up to run the South along capitalist lines, the North being run under a Communist regime, with the intention of unifying the country once open and fair elections could take place. Of course this never happened and the country was then set on a course for the second Vietnam war, this time featuring America and her Allies coming to the aid of the South Vietnamese. The rest as we know is history.