Its rapid territorial expansion started late in the reign of Gediminas,[11] and continued under the co-leadership of his sons, Algirdas and Kęstutis.

The battle provided a break in the wars with the Knights, and Lithuania exploited this situation, arranging attacks on the Ruthenian provinces and annexing Navahrudak and Hrodna.

He promised to convert to Christianity and exchange some lands in western Lithuania in return for military assistance against his nephews and the royal crown.

Vytenis was involved in succession disputes in Poland, supporting Boleslaus II of Masovia, who was married to a Lithuanian duchess, Gaudemunda.

In Ruthenia, Vytenis managed to recapture lands lost after the assassination of Mindaugas and to capture the principalities of Pinsk [lt] and Turov.

While almost every other state around it had been plundered or defeated by the Mongols, the hordes stopped at the modern borders of Belarus, and the core territory of the Grand Duchy was left mostly untouched.

[72] In 1380, a Lithuanian army allied with Russian forces to defeat the Golden Horde in the Battle of Kulikovo, and though the rule of the Mongols did not end, their influence in the region waned thereafter.

Under his rule, the Grand Duchy of Lithuania slowly became more centralized, as the governours loyal to Vytautas replaced local princes with dynastic ties to the throne.

[82] The rapid expansion of the influence of Moscow soon put it into a comparable position to the Grand Duchy of Lithuania, and after the annexation of Novgorod Republic in 1478, Muscovy was among the preeminent states in northeastern Europe.

Between 1492 and 1508, Ivan III further consolidated Muscovy, winning the key Battle of Vedrosha and capturing such ancient lands of Kievan Rus' as Chernihiv and Bryansk.

The battle was part of a long series of Muscovite–Lithuanian Wars conducted by Russian rulers striving to gather all the former lands of Kievan Rus' under their rule.

According to Rerum Moscoviticarum Commentarii by Sigismund von Herberstein, the primary source for the information on the battle, the much smaller army of Poland–Lithuania (under 30,000 men) defeated the 80,000 Muscovite soldiers, capturing their camp and commander.

[94] The Lithuanian lords, at a convention in Grodno (on 8-20 April 1576), protested this choice, threatening to break the union and giving themselves the right to choose a separate ruler.

[94] On May 29, 1580, in Vilnius Cathedral, King and Grand Duke Stephen Báthory received from the hand of the bishop of Samogitia Merkelis Giedraitis a blessed sword and hat, given by Pope Gregory XIII through the envoy Paweł Uchański.

[98][99] Báthory's reign was marked with successful Livonian campaign against tsar Ivan the Terrible's military forces, which resulted in the reintegration of Polotsk to Lithuania and the restoration of control of the Duchy of Livonia.

[100] The rule of Lithuania by the Gediminid–Jagiellonian family representatives resumed through matrilineal line following the death of Báthory (1586) when Sigismund III Vasa (son of Catherine Jagiellon) was elected in 1587.

[101] During the Polish–Swedish War (1600–1611) Polish and Lithuanian forces achieved victory and restored status quo ante bellum, notably winning the decisive Battle of Kircholm in 1605, while during the Polish–Muscovite War (1605–1618) Polish and Lithuanian armies achieved territorial gains (e.g. restored the control of Smolensk, the capital of the Smolensk Voivodeship, in 1611) and for the first time fully captured Russia's capital Moscow in 1610.

Soon after his arrival in Vilnius, Napoleon proclaimed the creation of a Commissary Provisional Government of the Grand Duchy of Lithuania which, in turn, renewed the Polish-Lithuanian Union.

Until the 17th century, there were relics of old faith reported by counter-reformation active Jesuit priests, like feeding žaltys with milk or bringing food to graves of ancestors.

The lands of modern-day Belarus and Ukraine, as well as local dukes (princes) in these regions, were firmly Orthodox Christian (Greek Catholic after the Union of Brest), though.

[citation needed] Islam in Lithuania, unlike many other northern and western European countries, has a long history starting from 14th century.

[123] Small groups of Muslim Lipka Tatars migrated to ethnically Lithuanian lands, mainly under the rule of Grand Duke Vytautas (early 15th century).

[143] In addition, Livonia, which had been politically connected to the Grand Duchy since the mid-16th century, was inhabited by Latgalians who spoke a dialect of the Latvian language.

[155][156][157] The Lithuanian language was still strongly present at the Vilnius court of Casimir Jagiellon, who had to learn it when he assumed power in the Grand Duchy in 1444.

[181] By the time of the largest expansion towards Rus' lands, which came at the end of the 13th and during the 14th century, the territory of the Grand Duchy of Lithuania was 800 to 930 thousand km2, just 10% to 14% of which was ethnically Lithuanian.

Because of strong enemies in the south and north, the newly formed Lithuanian state concentrated most of its military and diplomatic efforts on expansion eastward.

While there were certainly substantial regional differences in Kievan Rus', it was the Lithuanian annexation of much of southern and western Ruthenia that led to the permanent division between Ukrainians, Belarusians, and Russians, and even four Grand Dukes of Lithuania are appeared on the Millennium of Russia monument.

In the 19th century, the romantic references to the times of the Grand Duchy of Lithuania were an inspiration and a substantial part of both the Lithuanian and Belarusian national revival movements and Romanticism in Poland.

A failed attempt was made in 1918 to revive the Kingdom under a German Prince, Wilhelm Karl, Duke of Urach, who would have reigned as Mindaugas II of Lithuania.

According to the 10th article of the Law on the State Flag and Other Flags of the Republic of Lithuania (Lithuanian: Lietuvos Respublikos valstybės vėliavos ir kitų vėliavų įstatymas), adopted by the Seimas, the historical Lithuanian state flag (with horseback knight on a red field, which initial design dates back to the reign of Grand Duke Vytautas the Great)[194] must be constantly raised over the most important governmental buildings (e.g. Seimas Palace, Government of Lithuania and its ministries, Lithuanian courts, municipal council buildings) and significant historical buildings (e.g. Palace of the Grand Dukes of Lithuania, Trakai Island Castle), also in Kernavė and in the site of the Senieji Trakai Castle.