During the Russo-Swedish War (1495–1497), 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 (drawn from the cities of Moscow, Novgorod, and Tver, as well as from Pskov – which was not formally part of Muscovy until 1510) 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.