Please answer a question about the following article about Dwight D. Eisenhower:

Eisenhower did provide France with bombers and non-combat personnel. After a few months with no success by the French, he added other aircraft to drop napalm for clearing purposes. Further requests for assistance from the French were agreed to but only on conditions Eisenhower knew were impossible to meet allied participation and congressional approval. When the French fortress of Dien Bien Phu fell to the Vietnamese Communists in May 1954, Eisenhower refused to intervene despite urgings from the Chairman of the Joint Chiefs, the Vice President and the head of NCS.

When did Dien Bien Phu fall to the communists?
May 1954