During the German assault on the Military Transit Depot, Guardhouse nr. 1 was the most important stronghold in the defence of the Westerplatte peninsula. The crew managed to hold out till the end. After the war the Guardhouse was moved about 40 meters to allow for the expansion of the harbour. It is now a branch of the Gdańsk History Museum.

Because of its location, Guardhouse nr. 1 was the most important link in the chain of defence on the Westerplatte peninsula. The guardhouse crew consisted of 13 soldiers commanded by Leading Seaman Piotr Buder. On 1 September, during the German attack on the Military Transit Depot, some of the men from the abandoned Prom outpost moved to Guardhouse nr. 1 with their machine guns. The crew grew to 21 soldiers, equipped with three heavy machine guns and four light machine guns.

On 2 September a close hit damaged the guardhouse; the defenders replaced the torn-out door with a provisional barricade to prevent the attackers from throwing in a grenade. Despite the continually deteriorating conditions, the guardhouse crew held its position.

After the War, plans to enlarge the port threatened the abandoned and neglected Guardhouse nr. 1. In March 1967, thanks to the efforts of Westerplatte veterans and community activists, a special track was used to move the 600 tons building by a few dozen metres. In 1974 an exhibition room was opened in the renovated guardhouse. In 1980 the guardhouse became a branch of the Gdańsk History Museum. Today, a railway siding runs through its original location and a foundation slab remains underground.