Explanation: Fort Vaux was a bunker held by the French in WW1. Some 150 French soldiers held out against the continuous attack of thousands of German troops. In that time, the French troops were bombarded, burned out with flamethrowers, attacked with chemical gas, and driven deep into the bunker where they fought hand-to-hand over makeshift barricades in the corridors, and asked for friendly artillery to bombard their own position. They took a terrible toll on the German troops, with the bunker too well-fortified for the explosives on hand to destroy, and every inch of it covered by French guns over narrow chokepoints. Hard to miss a man-sized target in a man-sized hall.
The French were entirely surrounded and cut off from allied forces - even water ran out, as the fort was meant to resist an assault, not a damn siege. After several days without water, men were so desperate that they would try to lick the moisture off the bunker walls. Only after it was apparent death by dehydration was imminent did they finally concede that further resistance was futile, and offer their surrender.