1954
Battle of Dien Bien Phu
The setting
Dien Bien Phu valley, northwestern Tonkin, French Indochina (present-day Dien Bien province, Vietnam)
A remote upland valley basin ringed by forested hills; the French built a fortified airhead of strongpoints on the valley floor, dependent entirely on air resupply, while the Viet Minh held the dominating high ground around it.
Reveal the outcome
Recorded sideViet Minh (Democratic Republic of Vietnam)
Recorded resultDecisive victory; garrison overrun and forced to surrender
Viet Minh forces besieged and overran the French garrison, which surrendered on 7 May 1954.
How the atlas explains it
Giap inverted the French plan: by emplacing artillery and anti-aircraft on the surrounding heights and sustaining a massive porter-and-bicycle logistics effort, the Viet Minh neutralized French air resupply and firepower, then used siege engineering and attrition to grind down the encircled, undersupplied garrison.
What followed
Ended the First Indochina War and effectively French colonial rule in Indochina, leading to the 1954 Geneva Accords and the partition of Vietnam; a landmark anti-colonial victory.