The siege of Marienburg was an unsuccessful two-month siege of the castle in Marienburg (Malbork), the capital of the monastic state of the Teutonic Knights. The joint Polish and Lithuanian forces, under command of King Władysław II Jagiełło and Grand Duke Vytautas, besieged the castle between 26 July and 19 September 1410 in a bid for complete conquest of Prussia after the great victory in the Battle of Grunwald (Tannenberg). However, the castle withstood the siege and the Knights conceded only to minor territorial losses in the Peace of Thorn (1411). Marienburg defender Heinrich von Plauen is credited as the savior of the Knights from complete annihilation.