The following year, the Livonian Order, a branch of the Teutonic Knights, occupy Pskov, hoping to exploit Novgorod's weakness in the wake of the Mongol and Swedish invasions, but Yaroslavich successfully liberates the city. Determined to push the Order out of Russia, he marches to Lake Peipus, and in the Battle on the Ice, his troops engage with the Order on the frozen lake. Defeating them, Alexander is able to drive the invaders back, halting their eastward expansion.