While the Treaty of Versailles put an end to World War I in 1919, it did not resolve the contentious issues in the Polish-German relations. The bone of contention was, among other matters, Gdańsk— under the Treaty of Versailles of 28 June 1919 it was declared a free city. The Polish interests were safeguarded by: the General Commissariat of the Republic of Poland, the Delegacy of the Attorney General’s Office, the Chief Customs Inspectorate, the Polish State Railways, the Polish Delegacy of the Port and Waterways Council, the Polish Post Office, the Polish Telegraph Agency, etc. Poland was entitled to maintain a sentry detachment with its headquarters on the Westerplatte peninsula as the Military Transit Depot. The Polish inhabitants constituted approximately 10 per cent of the overall population of Gdańsk. However, it is unknown exactly how numerous the Polish community was. The estimated number is 9,000 people. Poles were repeatedly harassed by both the local authorities and the German population. On 1 September 1939 at 4:48 am, the battleship Schleswig-Holstein opened fire on the Polish Military Transit Depot on Westerplatte. These shots marked the outbreak of World War II. On the same day, an assault was launched on the building of the Polish Post Office in the Free City of Gdańsk. The assault was carried out by a special division of the Schutzpolizei (Protection Police) and the SS subdivisions: Wachsturmbann “Eimann” and SS-Heimwehr Danzig. The acting director of post offices and telegraphs was Dr Jan Michoń, and the man in charge of the defence of the building was explosives engineer Reserve 2 Lt Konrad Guderski, alias “Konrad”, a civilian employee of the 2nd Division of the Central Staff of the Polish Armed Forces. He was killed at the beginning of the defence by a grenade blast and then the command was taken over by his deputy Alfons Flisykowski. The post office employees put up strong resistance. Following the initial unsuccessful attacks, the Germans introduced two armoured cars into the action: SS-Ostmark and SS-Sudetenland. They used hand grenades and artillery: a 105 mm howitzer and two infantry guns. The postmen surrendered only after the Germans used armoured weapons and flamethrowers. Six Poles were killed. The reverse of the coin features the images of Dr Jan Michoń, Alfons Flisykowski and Reserve 2 Lt Konrad Guderski against the main entrance to the Post Office building. The obverse features the main entrance to the Post Office building against the destroyed façade of the building. The design is complemented by the Polish Post Office symbol.