It appears May 7 was very significant multiple times since it also includes the Vietnamese defeating the French at Dien Bien Phu, causing the French to leave their colony to the natives. Both surrenders, German and French, figured greatly into US history in the final half of the 20th Century.
We originally supported Vietnamese nationalism following World War II and OSS agents were on hand for Ho Chi Minh’s declaration of independence ceremony (standing shoulder-to-shoulder with Gen. Giap), with U.S. planes performing a flyover.
Our involvement in Vietnam was basically diplomatic blackmail by the French. They wanted to keep French Indochina as a colony, and let us know that it would be a shame if they couldn’t join us in confronting the Soviet Union because they were spending money and losing lives fighting to keep up their colonial rule of Southeast Asia.
In hindsight, I don’t know that France was much use to the West during the Cold War, and Vietnam was very pro-U.S. and independent of both China (whom they despised) and the Kremlin.