In the summer, 70 vessels carrying Knut Posse, Svante Nilsson, and 2,000 men enter the river Narva and managed to penetrate 20 kilometers upstream towards Ivangorod.

The prosperous town presented the Swedes with an excellent strategic objective for a Swedish counterstrike in retaliation for the earlier siege of Viborg.

[2] In just a few hours, the attacking Swedes bombarded the riverbanks and the fortress, landed, moved the guns to batteries quickly built ashore, and breached Ivangorod.

[7][5][2] Ivan III was determined to keep his foothold in the Baltics, and the Russians rebuilt the fortress into a larger, quadrilateral structure which was extended toward the border with Livonia.

In order to draw up instructions for the Swedish envoys, Knut Posse and other commanders at Viborg held a meeting in Borgå with Bishop Magnus.