 Cogny was one of many officers who protested against this new strategy, stating that "we are running the risk of a new Na San under worse conditions" (Na San was successfully defended during a nine-day siege but was thereafter evacuated).These protests, however, had no effect.Though stationed in Hanoi during the Battle of Dien Bien Phu itself, having seen the battle turning against France, Cogny attempted to reach the besieged garrison to take command; however, his aircraft was beaten back by anti-air fire on 17 March 1954.