Truce of Yam-Zapolsky: Russia cedes Livonia to the Polish–Lithuanian Commonwealth.

The Truce or Treaty of Yam-Zapolsky (Ям-Запольский) or Jam Zapolski, signed on 15 January 1582 between the Polish–Lithuanian Commonwealth and the Tsardom of Russia, was one of the treaties that ended the Livonian War. It followed the successful Livonian campaign of Stephen Báthory, culminating in the siege of Pskov.

Livonia, known in earlier records as Livland, is a historical region on the eastern shores of the Baltic Sea. It is named after the Livonians, who lived on the shores of present-day Latvia.

The Polish–Lithuanian Commonwealth, also referred to as Poland–Lithuania or the First Polish Republic, was a federative real union between the Kingdom of Poland and the Grand Duchy of Lithuania, existing from 1569 to 1795. This state was among the largest, most populated countries of 16th- to 18th-century Europe. At its peak in the early 17th century, the Commonwealth spanned approximately 1,000,000 km² (390,000 sq mi) and supported a multi-ethnic population of around 12 million as of 1618. The official languages of the Commonwealth were Polish and Latin, with Catholicism as the state religion.

January 15 is the 15th day of the year in the Gregorian calendar; 350 days remain until the end of the year.