The Grand Duchy of Lithuania is a European state from the 12th century until 1795.

It is founded by the Lithuanians, one of the polytheistic Baltic tribes from Aukštaitija.

The duchy later expands to include large portions of the former Kievan Rus' and other Slavic lands, covering the territory of present-day Belarus, Latvia, Lithuania and parts of Estonia, Moldova, Poland, Russia and Ukraine.

At its greatest extent in the 15th century, it is the largest state in Europe.

It is a multi-ethnic and multi-confessional state with great diversity in languages, religion, and cultural heritage.Consolidation of the Lithuanian lands begins in the late 12th century.

Mindaugas, the first ruler of the Grand Duchy, is crowned as Catholic King of Lithuania in 1253.

The pagan state is targeted in the religious crusade by the Teutonic Knights and the Livonian Order.

The multi-ethnic and multi-confessional state emerges only at the late reign of Gediminas and continues to expand under his son Algirdas.Algirdas's successor Jogaila signs the Union of Krewo in 1386, bringing two major changes in the history of the Grand Duchy of Lithuania: conversion into Catholicism 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 marks 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 marks the rise of the Lithuanian nobility.

After Vytautas's death, Lithuania's relationship with the Kingdom of Poland greatly deteriorates.

Lithuanian noblemen, including the Radvila family (Radziwills), attempt to break the personal union with Poland.

However, the unsuccessful Muscovite–Lithuanian Wars with the Grand Duchy of Moscow force the union to remain intact.Eventually, the Union of Lublin of 1569 creates a new state, the Polish–Lithuanian Commonwealth.

In this federation, the Grand Duchy of Lithuania maintains its political distinctiveness and has a separate government, laws, army, and treasury.

This federation ss terminated by the passing of the Constitution of May 3, 1791, and from that time is supposed to be but a single country — Respublica Poloniae — under one monarch and one parliament.

Shortly after, the unitary character of the state is confirmed by adopting Reciprocal Guarantee of Two Nations.

The newly reformed Commonwealth is invaded by Russia in 1792, and partitioned between the neighbors, with a truncated state (principal cities being Kraków, Warsaw and Vilnius) remaining only nominally independent; and after the Kościuszko Uprising, partitioned among the Russian Empire, the Kingdom of Prussia and Austria in 1795.