 Complete the following phrase:  After the initial battles in Pomerelia, the remains of the Polish Army of Pomerania withdrew to the southern bank of the Vistula river. After defending Toruń Thorn for several days, the army withdrew further south under pressure of the overall strained strategic situation, and took part in the main battle of Bzura. On the borders of the Free City of Danzig, there were two fortified Polish points: the Polish post office in Danzig and the Polish ammunition store on the Westerplatte. Both were ordered to defend up to 12 hours in case of local uprising, until an expected relief by the Polish army. The Polish Post office was held by 52 employees led by Konrad Guderski against the German Danzig police, Home Guard Heimwehr and SS, which after 14 hours of battle set the building on fire with flamethrowers. All but four postman who escaped either died in the battle or were executed by the Germans as partisans only in 1995 did the German court at Lübeck invalidate the 1939 ruling and rehabilitate the postmen. The Polish Military Transit Depot Polska Wojskowa Składnica Tranzytowa on the Westerplatte repelled countless attacks by the Danzig Police, SS, the Kriegsmarine and the Wehrmacht. Finally, the Westerplatte crew surrendered on 7 September, having exhausted their supplies of food, water, ammunition and medicines, becoming one of the symbols of Polish resistance to the German invasion. The heaviest fighting in Pomerelia took place at the Hel peninsula Polish Navy base, which held out as one of the last centres of Polish military resistance until October 3, 1939 see 