The Grand Duchy of Lithuania was a European state that existed from the 13th century to the late 18th century, when the territory was partitioned in 1795 among the Russian Empire, the Kingdom of Prussia, and the Habsburg Empire of Austria. The state was founded by Lithuanians, who were at the time a polytheistic nation born from several united Baltic tribes from Aukštaitija.
The Grand Duchy expanded to include large portions of the former Kievan Rus' and other neighbouring states, including what is now Belarus, Lithuania, most of Ukraine as well as parts of Latvia, Moldova, Poland and Russia. At its greatest extent, in the 15th century, it was the largest state in Europe. It was a multi-ethnic and multiconfessional state, with great diversity in languages, religion, and cultural heritage.
The consolidation of the Lithuanian lands began in the late 13th century. Mindaugas, the first ruler of the Grand Duchy, was crowned as Catholic King of Lithuania in 1253. The pagan state was targeted in a religious crusade by the Teutonic Knights and the Livonian Order, but survived. Its rapid territorial expansion started late in the reign of Gediminas, and continued under the diarchy and co-leadership of his sons, Algirdas and Kęstutis. Algirdas's son Jogaila signed the Union of Krewo in 1386, bringing two major changes in the history of the Grand Duchy of Lithuania: conversion to Christianity of Europe's last pagan state, and establishment of a dynastic union between the Grand Duchy of Lithuania and the Crown of the Kingdom of Poland.
The reign of Vytautas the Great, son of Kęstutis, marked both the greatest territorial expansion of the Grand Duchy and the defeat of the Teutonic Knights in the Battle of Grunwald in 1410. It also marked the rise of the Lithuanian nobility. After Vytautas's death, Lithuania's relationship with the Kingdom of Poland greatly deteriorated. Lithuanian noblemen, including the Radvila family, attempted to break the personal union with Poland. However, unsuccessful wars with the Grand Duchy of Moscow forced the union to remain intact.