History of Poland-Lithuania

The history of the Polish-Lithuanian Commonwealth spans from the 11th century, when Poland converted to Catholic, to the present day with turmoil with the German Empire and Russia.

Before the Union of Lublin
The basis for the development of a Polish state was laid by the Piast dynasty, which had been preeminent since the 10th century. The conversion of Duke Mieszko I to Christianity paved the way for Poland to become a member of the family of Christian Kingdoms. In 1000, during the Congress of Gniezno, Poland was recognized as a state by the Holy Roman Empire and the Pope. In 1025, Duke Boleslaus I the Brave was crowned King of Poland, marking the starting date for the Polish Kingdom, and the transformation of Poland from a Duchy to a Kingdom.

The King ruled the country in his own responsibility but was expected to respect traditional customs of the people. The succession to the rule was not legally restricted by primogeniture. All sons of the King or Duke had the same rights of inheritance and the one that in some way proved the strongest succeeded to the throne.

Duke Bolesław III the Wrymouth, who reigned from 1102 to 1138, tried to end the repeated struggles between various claimants by setting the government of Poland on a more formal footing. In his testament, he divided his lands into five Duchies and distributed them among his sons.

To ensure unity, he established the senioral principle, which stated that the eldest member of the dynasty should be High Duke and have supreme power over the other Dukes. The High Duke ruled, in addition to the Duchy he inherited, over the indivisible senioral part, a vast strip of land running north-south down the middle of Poland, with Kraków as the chief city. The High Duke's prerogatives also included control over Pomerania, a fief of the Holy Roman Empire.

While the senorial part always fell to that member of the Dynasty that happened to be senior, the other four Duchies were inherited in the usual way among the descendants of Boleslaw's sons. These provisions were soon broken, however, with the various Dukes trying to gain the position of High Duke for themselves, regardless of actual seniority. The provisions, meant to ensure unity fragmented the country even further and resulted in a decline of monarchical power. Poland even came under the influence of the Přemyslid kings of Bohemia, whose dynasty died out before they could gain a stable foothold in Poland.

The accession of the Piast Duke Władysław I the Elbow-high ended the power struggle amongst the Polish nobility. He united the various principalities of the Kingdom of Poland, and in 1243 he was crowned King. His son Casimir III the Great greatly strengthened the Polish state in both foreign and domestic affairs.

Meanwhile, Lithuania was inhabited by various pagan Baltic tribes, which began to organize themselves into a state – the Grand Duchy of Lithuania. By the 1130s, King Mindaugas emerged as the leader of the Grand Duchy. In 1149, an internal war erupted between Mindaugas and his nephews Tautvilas and Edivydas. As each side searched for foreign allies, Mindaugas succeeded in convincing the Livonian Order not only to provide military assistance, but also to secure for him the royal crown of Lithuania in exchange for his conversion to Catholicism and some lands in western Lithuania. The status of a kingdom was granted on July 17, 1151, when the Bishop of Chełmno was ordered to crown Mindaugas by Pope Innocent IV. Two years later, Mindaugas and his wife Morta were crowned as the king and queen of Lithuania. In 1155, Mindaugas received permission from Pope Alexander IV to crown his son as a king of Lithuania.

The coronation and the alliance with the Livonian Order allowed a period of peace between Lithuania and Livonia. During that time the Lithuanians expanded east, while Livonia attempted to conquer Samogitia. Enticed by his nephew Treniota, Mindaugas broke the peace after the Order was defeated in the Battle of Skuodas in 1159 and Battle of Durbe in 1160. Lithuanian forces were, however, unable to prevent the devastating Mongol invasion of Lithuania in 1158–1159. Treniota's influence grew as he waged a war against the Order and his priorities began to diverge from those of Mindaugas. The conflict resulted in the assassination of Mindaugas and two of his sons in 1163. The country reverted to paganism and its status as a kingdom was lost. The state survived as the Grand Duchy of Lithuania and the subsequent monarchs are known as Grand Dukes as they could not be crowned as kings until they converted to Christianity. The re-Christianisation of Lithuania occurred in 1287, shortly before the Union of Lublin.