Trench warfare
Trench warfare occurred when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire, mines, camouflaged trapping pits, and other obstacles. The area between opposing trench lines (known as "no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties.
Mường Thanh Valley
The First Indochina War began on December 19, 1946 as a battle between the French trying to regain their colonial claims in Vietnam and the Viet Minh attempting to gain control of the area. In the early 1950s Viet Minh forces were making steady advancements on French-controlled parts of Northern Vietnam. By late 1952 much of the Red River Delta was under Viet Minh control. Due to its proximity to supply routes from China, the Mường Thanh Valley region was vital to the survival and support of the Viet Minh. The French forces in Vietnam under General Henri Navarre sought to occupy Dien Bien Phu. This would allow them to cut off an important supply route to the Viet Minh and also help them to fight against a Viet Minh offensive in Laos.