De Castries' seclusion in his bunker, combined with his superiors' inability to replace him, created a leadership vacuum in the French command. On 24 March, an event took place which later became a matter of historical debate. The historian Bernard Fall records, based on Langlais' memoirs, that Colonel Langlais and his fellow paratroop commanders, all fully armed, confronted de Castries in his bunker on 24 March. They told him he would retain the appearance of command, but that Langlais would exercise it. De Castries is said by Fall to have accepted the arrangement without protest, although he did exercise some command functions thereafter. Phillip Davidson stated that the "truth would seem to be that Langlais did take over effective command of Dien Bien Phu, and that Castries became 'commander emeritus' who transmitted messages to Hanoi and offered advice about matters in Dien Bien Phu". Jules Roy, however, makes no mention of this event, and Martin Windrow argues that the "paratrooper putsch" is unlikely to have ever happened. Both historians record that Langlais and Marcel Bigeard were known to be on good terms with their commanding officer.