in 1408, vytautas reached peace in the east and returned to samogitian matters. in 1409 the second samogitian uprising against the teutonic knights began, as the rebels burned skirsnemunė castle. both poland and lithuania supported the rebels. vytautas gathered a large army from 18 lands under his control. the army joined polish forces and advanced towards the teutonic headquarters at the castle of marienburg (present-day malbork). in 1410, vytautas himself commanded the forces of the grand duchy in the battle of grunwald, also called the battle of žalgiris (lithuanian) or tannenberg (german). the battle ended in a decisive polish-lithuanian victory. even though the siege of marienburg was unsuccessful, the teutonic knights never regained their strength and from then on posed a reduced threat to poland-lithuania.