The Siege of the Alcázar in the Spanish Civil War, in which the Nationalists held out against a much larger Republican force for two months until relieved, shows that in some cases a citadel can be effective even in modern warfare; a similar case is the Battle of Huế during the Vietnam war, where a North Vietnamese Army division held the citadel of Huế for 26 days against roughly their own numbers of much better-equipped US and South Vietnamese troops.