Fort de Vaux is smaller than Douaumont but in some ways more affecting. It is the site of the famous June 1916 siege in which a French garrison held out for a week against repeated German attacks despite gas, flamethrowers and grenades pumped down its corridors — surrendering only when the last water cistern ran dry.
The interior can be explored on a self-guided visit; the cramped, dark corridors give a clear sense of the conditions Raynal's men endured. There is a memorial to the carrier pigeon Vaillant outside, who carried out the final desperate message. Quieter than Douaumont and well worth combining with it.