According to the decision of the Council of the League of Nations dated 1924, from 1926 the Westerplatte peninsula was transferred to Poland for the purposes of an ammunition and weapons reloading depot. The 88 strong force of Polish soldiers was responsible for ensuring the security of the warehouses and the entire area of the Military Transit Depot. The military unit was changed every 6 months. To ensure better security of the warehouse area, four reinforced concrete guard post buildings were built in 1933 – 1934 and two years later an army barracks were built, which served as the command centre of the depot. In the summer of 1939, in light of the increased tension in Polish-German relations, the post’s forces were strengthened to the level of approx. 210 soldiers and reservists from civilian personnel.
The military post in 1938 was commanded by Major Henryk Sucharski and Captain Franciszek Dąbrowski was commander of the guard personnel. The post’s weapons consisted of Mauser guns, about 40 heavy and light machine guns, two 37mm bazookas, one old 75mm heavy gun and four 81mm mortars.
On 1 September 1939 the volley of 280mm guns from the German armoured ship “Schleswig Holstein”, which visited Gdańsk on a peaceful mission, started an attack of infantry on the Polish post in Westerplatte. The Polish forces defended for 7 days against numerous attacks coming from the base of the peninsula. Bombarded from the air and by the heavy guns and mortars, the Polish soldiers stood their ground for 7 days. On 7 September 1939 in light of being completely outnumbered by the enemy and given the exhaustion of the soldiers, Major Henryk Sucharski decided to capitulate. Fifteen Polish soldiers died during the fighting and many were wounded. The German casualties are unknown. After surrendering, the Polish soldiers were sent to German POW camps, where they stayed until 1945.
During the entire Westerplatte battle, Guard Post No. 1 was the linchpin of the Polish defence. The fire from the bunker in the cellars and from the windows above ground prevented the Germans from breaking the Polish lines from the base of the peninsula or the harbour channel. The building’s structure, though affected by heavy machine gunfire and gun shells, remained undamaged. The platoon leader, Piotr Buder, was the commander of the crew of this heroic point of Polish defence.
Only Guard Post No. 1, the former power plant building and the ruins of the army barracks remain from the former facilities of the Polish military post in Westerplatte. In 1967 Guard Post No. 1 was moved under a complex technical operation to its present location in order to save it from demolition, as it was located in an area of the harbour wharf – now a ferry harbour.
In June 1974, a Commemoration Room was created in Guard Post No. 1, which in 1980 was transformed into a Branch of the Gdańsk History Museum, which exists to date. Former defenders of Westerplatte from 1939 - Franciszek Bartoszak, Bernard Rygielski, Wiktor Ciereszko and Julian Dworakowski were for many years the caretakers of the exhibition in the Guard Post.
According to the concept adopted in 1974, the exhibition in the Guard Post reflects its interior from September 1939 indicating the combat posts and presenting various items illustrating the history of Westerplatte to 1939.