The Battle of Dong Khe was a major battle of the First Indochina War. The fight began on September 15, 1950 and ended on September 18 with a French defeat. Combatants French Union France State of Vietnam Viet Minh Commanders Philippe Leclerc de Hauteclocque (1945-46) Jean-Étienne Valluy (1946-8) Roger Blaizot (1948-9) Marcel-Maurice Carpentier (1949-50) Jean de Lattre de Tassigny (1950-51) Raoul Salan (1952-3) Henri Navarre (1953-4) Ho Chi Minh Vo Nguyen... September 15 is the 258th day of the year (259th in leap years) in the Gregorian calendar. ... September 18 is the 261st day of the year (262nd in leap years). ...

Source

Erwan Bergot, La bataille de Dong Khê. Paris: Presses de la Cité, 1987.