The Battle of the Siritsa River took place on 27 August 1501 between the forces of the Livonian Order under Grand MasterWolter von Plettenberg on the one side and the forces of the Grand Duchy of Moscow and Pskov Republic on the other. The Russian forces were soundly defeated. Grand PrinceIvan III of Russia pursued expansionist policies, which strained Moscow's relations with Livonia. In 1492, Moscow built Ivangorod Fortress opposite of Narva and two years later closed down the Hanseatic office in Novgorod. Hanseatic merchants, most of them Livonians, were imprisoned. The trade through Tallinn and Tartu diminished significantly. During the Russo-Swedish War, Sweden captured Ivangorod and offered it to Livonia, an offer which was refused. Moscow perceived that as a Swedish–Livonian alliance. As negotiations failed, Livonia began preparing for war. In May 1500, a war broke out between Moscow and the Grand Duchy of Lithuania. On 17 May 1501, Livonia and Lithuania concluded a ten-year alliance in Vilnius. In August 1501, von Plettenberg led a Livonian army, reinforced with 3,000 mercenaries from Lübeck, towards Pskov. The armies met on 27 August 1501 on the Siritsa River, 10 km south from Izborsk, on the western approaches to Pskov. The Pskovian regiment attacked the Livonians first but was thrown back. The Livonian artillery then destroyed the remainder of the Muscovite army despite a Russian attempt to reply with their own, insufficient, artillery force. In the battle, the smaller Livonian army defeated the Muscovite army in large part due to the Order's formidable artillery park and the Russians' significant shortage of guns of any kind. The defeat prompted Moscow to modernize its army by creating standing infantry units armed with arquebus. Livonian troops then captured Ostrov and unsuccessfully besieged Pskov. The Russians retaliated by invading and plundering eastern Livonia and defeating the Order at Helmed near Dorpat. The Order won a victory at the Battle of Smolinin September 1502. The war ended in 1503 when Lithuania sued for peace. Peace between Livonia and Moscow lasted until the Livonian War.
