The evidence for the costs can be found in many different sources which show that in 1945, the French military expenditure in Indochina was 3200 million francs. Most of this was provided by the U.S. Year by year this amount grew tremendously and this is shown in that in 1948 the amount had increased to 89700 million francs, in 1950 it was 201000 million francs and finally in 1952 the amount was 435000 (estimate) million francs. U.S.A was providing too much money for the French. This, plus the fact that the French were losing too many men gave the Vietminh a good signal that they were winning this unconventional war, with their traditional equipment through guerilla warfare.
Due to the high toll of deaths, prisoners and wounded men, support from the people back in France suddenly decreased and they were thinking that they could not allow any more troops to go to Vietnam, as most of them would not come back. Also, the people of France had grown to the end of their tether because of the amount of money that was being used in a war where France was fighting against conventional weapons, was at such a high amount that worried everyone. They were tired of war. French had even blamed that the U.S were not supporting them enough, including when they asked for helicopters to shoot down the Vietminh which the U.S disagreed to, mostly due to the case that they had just completed their own war. The French Union soldiers had treated the villages poorly, taking food and drink and ill-treating both peasants and prisoners.
Due to the fact that the French were not going to be supported by the Vietnamese so they could not strengthen their army any longer and this would add to another success of Vietnamese. The Vietminh was now stronger than the French and as the war went on the Vietminh had a better geographical knowledge and so their guerilla warfare was a real threat against the French. As you can see from above, the main reason which cost against the French linked to the support they were given which was linked against the strength and knowledge of the Vietminh. In November 1953, the French sent their crack paratroop regiment to Vietnam. It was naturally assumed by the French that this unit would sort out the untrained Viet Minh guerillas. They were sent to Dien Bien Phu in the north. In May 1954, the regiment surrendered which came as a terrible blow to the French people. The French pulled out of Vietnam in the same month. With the help from some sources we are told that the Vietminh were running pout of resources whilst the French supplies kept coming on, if the French had stayed in Vietnam a little more time beyond 1954 they would have been able to destroy they Vietminh.
The French had got themselves into a difficult military position. Despite huge American help, the French could not cope with the Vietminh's guerilla tactics. The Vietminh were by now receiving help from Communist China - Mao Tse Tung had taken power of China in 1949. The fact that two sides had developed was classic history.
We can see that the cost to France was a significant point in making them choose to leave Vietnam in 1954. This was linked to other things such as the support they got from different factors. These were also vital in them losing at Dien Bien Phu which was a short term cause of France’s retreat from Vietnam.
In 1954 French quickly retreated due their last strongpoint being overrun by the Vietminh. I believe that the most important trigger for this was the cost towards the French which then triggered other factors, which all led to them being overrun.
To summarise, French support was weak due to the cost, their army and knowledge was weak due to them not getting much support except from U.S.A, and finally their army was too weak which led to them losing at Dien Bien Phu. And last but not least, French themselves were being too greedy trying to get Vietnam back, who had turned independent then and so the Vietminh with no compensation fought for their country and beat the French.
