Maps of Decisive Phases of the Siege of Dien Bien Phu

On the blog today, Kevin Boylan, one of the authors of Valley of the Shadow: The Siege of Dien Bien Phu looks at the decisive phases of the Siege of Dien Bien Phu accompanied with fantastic maps.

The 1954 siege of Dien Bien Phu is one of the epics of 20th century military history, featuring dramatic assaults, daring sorties, desperate counterattacks, and doomed last stands spread over 56 gruelling days. But the decisive battles that decided the outcome of the siege – and the First Indochinese War – were mostly crowded into three short periods when the Vietnamese People’s Army (VPA) launched major offensives against the French garrison. The first VPA offensive of March 13–17 captured three isolated clusters of French strongpoints (codenamed Beatrice, Gabrielle and Anne Marie) that dominated the northern part of the valley. Yet the loss of these positions did not fatally undermine the integrity of the French air-land base, which still comprised the ‘Main Position’ – a dense cluster of strongpoints surrounding the main airstrip – and ‘Isabelle’ – an artillery firebase three miles south of it. The VPA spent the latter half of March digging a huge network of trenches around these positions and fighting daily battles to prevent powerfully escorted French supply convoys from moving between them. Isabelle was irrevocably cut off at the end of the month and fought in isolation for the remainder of the siege.

The truly decisive battles were therefore fought on and around the Main Position, which was the target of Vietnamese People’s Army’s second and third offensives. The second began on the night of March 30–31 with a massive frontal assault on five crucial French hill strongpoints by elements of the VPA’s 308th, 312th and 316th Infantry Divisions. Three of the hills were lost within 24 hours, but the southernmost two (‘Eliane-2’ and ‘Eliane-4’) held out through another five days and nights of intense battles fought at point blank range. During this period, battles were also fought west of the Nam Yum River, where VPA troops battled just as fiercely to capture the ‘Huguette’ strongpoints that guarded the crucial airstrip. The second VPA offensive ended on the morning of April 5 after a series of French counterattacks turned the VPA 165th Regiment’s assault on strongpoint Huguette-6 into a bloody disaster.

Five days later, the French further disrupted VPA plans by mounting a counterattack that recaptured one of the Five Hills – strongpoint Eliane-1. After this setback, the besiegers spent the rest of April conquering the airport piece by piece, gradually strangling the French by seizing the drop zone on which they were totally dependent for parachuted supplies and reinforcements. With the defenders thus critically weakened, the third VPA offensive began on the night of May 1–2 with simultaneous assaults on both flanks of the Main Position. This touched off another six days of intense combat that culminated on the night of May 6–7, when VPA troops captured four key strongpoints, and the defenders expended the last of their reserves and artillery ammunition. They were forced to surrender before nightfall on May 7, and the isolated strongpoint Isabelle had to follow suit shortly after midnight following the failure of an attempted breakout.

The following four maps depict the key battles that ‘bookended’ the VPA’s second and third offensives. The codes printed alongside the arrows showing lines of movement and assault indicate battalion/regiment wherever two numbers are listed, and company/battalion/regiment in those cases where three numbers appear. Thus ‘81/439/98’ signifies the 81st Company, 439th Battalion, 98th Infantry Regiment (of the 316th Infantry Division). The letter/number designations represent French codenames for strongpoints, for example ‘E1’ for Eliane-1; the other strongpoints marked in this way belong to Dominique, Huguette, Claudine and Lily. The details of battles for individual strongpoints can be found in Valley of the Shadow: The Siege of Dien Bien Phu by Kevin Boylan and Luc Olivier, published by Osprey in 2018.

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Order your copy of Valley of the Shadow: The Siege of Dien Bien Phu from the website here.