The Battle of wiecino (named for the village of wiecino, near arnowiec Lake, northern Poland) also called the Battle of arnowiec or in German Die Schlacht bei Schwetz, took place on September 17, 1462 during the Thirteen Years' War. The Polish forces, commanded by Piotr Dunin and consisting of some 2,000 mercenaries and Poles, decisively defeated the 2,700-man army of the Teutonic Knights, commanded by Fritz Raweneck and Commander of the Order Kaspar Nostitz (Nostyc). Auxiliary forces sent by Duke Eric II of Pomerania, temporary ally of the Teutonic Knights, did not enter the battle.

Piotr Dunin (c. 1415 – 1484) was a Polish leader. Starost of Malbork 1478–1484, castellan of Sieradz from 1478, voivode of Brześć Kujawski Voivodeship from 1481.

On 17 September 1462 he led the Polish army to victory over the Teutonic Knights in the Battle of Świecino. This Thirteen Years' War battle brought an end to Teutonic control of the region, as the Knights never recovered from it and those that followed.