By December 1409 Władysław II Jagiełło and Vytautas had agreed on a common strategy: their armies would unite into a single massive force and march together towards Marienburg (Malbork), capital of the Teutonic Knights.[30] The Knights, who took a defensive position, did not expect a joint attack and were preparing for a dual invasion—by the Poles along the Vistula River towards Danzig (Gdańsk) and the Lithuanians along the Neman River towards Ragnit (Neman).[1] To counter this perceived threat, Ulrich von Jungingen concentrated his forces in Schwetz (Świecie), a central location from where troops could respond to an invasion from any direction rather quickly.[31] Sizable garrisons were left in the eastern castles of Ragnit, Rhein (Ryn) near Lötzen (Giżycko) and Memel (Klaipėda).[1] To keep their plans secret and mislead the knights, Władysław II Jagiełło and Vytautas organized several raids into border territories, thus forcing the knights to keep their troops in place.[30]