In 1386, Grand Duke Jogaila of Lithuania converted to Catholicism and married Queen Jadwiga of Poland. This act enabled him to become a king of Poland himself, and he ruled as Władysław II Jagiełło until his death in 1434. The marriage established a personal Polish–Lithuanian union ruled by the Jagiellonian dynasty. The first in a series of formal “unions” was the Union of Krewo of 1385, whereby arrangements were made for the marriage of Jogaila and Jadwiga. The Polish–Lithuanian partnership brought vast areas of Ruthenia controlled by the Grand Duchy of Lithuania into Poland’s sphere of influence and proved beneficial for the nationals of both countries, who coexisted and cooperated in one of the largest political entities in Europe for the next four centuries. In the Baltic Sea region, Poland’s struggle with the Teutonic Knights continued and culminated in the Battle of Grunwald (1410), a great victory. The Union of Horodło of 1413 further defined the evolving relationship between the Kingdom of Poland and the Grand Duchy of Lithuania. There were long discussions before signing the union treaty. Lithuanian magnates were afraid of losing much of their powers, since the union would make their legal status equal to that of the much more numerous Polish lower nobility. Lithuania had been increasingly on the losing side of the Muscovite-Lithuanian Wars, however, and by the second half of the 16th century, it faced the threat of total defeat in the Livonian war and incorporation into Russia. The Polish nobility (the szlachta), on the other hand, were reluctant to offer help to Lithuania without receiving anything in exchange. Nevertheless, the Polish and Lithuanian elites strengthened personal bonds and had opportunities to plan their united futures during increased military cooperation in the 1560s. Sigismund II Augustus, King of Poland and Grand Duke of Lithuania, seeing the threat to Lithuania and eventually to Poland, pressed for the union, gradually gaining more followers until he felt enough support to evict landowners forcibly who opposed the transition of territory from Lithuania to Poland. A clear motivation for Sigismund was that he was the last Jagiello and had no children or brothers who could inherit the throne. Therefore, the Union was an attempt to preserve the continuity of his dynasty’s work since the personal (but not constitutional) union of Poland and Lithuania at the marriage of Jadwiga of Poland and Wladyslaw II Jagiello. The Union was one of the constitutional changes required to establish a formal elected monarchy, which would simultaneously reign over both domains. The Sejm met in January 1569, near the Polish town of Lublin, but did not reach an agreement. One of the points of contention was the right of Poles to settle and own land in the Grand Duchy. After most of the Lithuanian delegation under the leadership of Vilnius Voivodeship’s Mikołaj “Rudy” Radziwiłł left Lublin on 1 March, the king announced the incorporation into the Crown of Podlachia, Volhynia and the Kiev palatinate (on 6 June), with wide approval from the local gentry. Bratslav and eastern Podolia were also transferred to Poland. Those historic lands of Rus’ are over half of modern Ukraine and were then a substantial portion of the Grand Duchy of Lithuania’s territory. The Rus’ nobles there were eager to capitalise on the economic and political opportunities offered by the Polish sphere, and by and large, they wanted their lands to become a part of the Polish Crown. The Lithuanians were forced to return to the Sejm under the leadership of Jan Hieronimowicz Chodkiewicz (father of Jan Karol Chodkiewicz) and to continue negotiations, using slightly different tactics from those of Radziwiłł. Though the Polish szlachta wanted full incorporation of the Grand Duchy of Lithuania into the Crown, the Lithuanians continued to oppose that and agreed only to a federal state. On 28 June 1569, the last objections were overcome, and on 4 July, an act was accordingly signed by the king at Lublin Castle. The Union of Lublin was signed on 1 July 1569, in Lublin, Poland, and created a single state, the Polish–Lithuanian Commonwealth. It replaced the personal union of the Crown of the Kingdom of Poland and the Grand Duchy of Lithuania with a real union and an elective monarchy, since Sigismund II Augustus the last of the Jagiellons, remained childless after three marriages. The Commonwealth was ruled by a single elected monarch who carried out the duties of King of Poland and Grand Duke of Lithuania, and governed with a common Senate and parliament (the Sejm). The Union was an evolutionary stage in the Polish–Lithuanian alliance and personal union, necessitated also by Lithuania’s dangerous position in wars with Russia. Constituting a crucial event in the history of several nations, the Union of Lublin has been viewed quite differently by many historians. Sometimes identified as the moment at which the szlachta (including Lithuanians/Ruthenians) rose to the height of their power, establishing a democracy of noblemen as opposed to absolute monarchy. Some Lithuanian historians are more critical of the Union, concluding it was an effect of domination by Polish nobles. The Union of Lublin of 1569 established the Polish–Lithuanian Commonwealth, a federal state more closely unified than the earlier political arrangement between Poland and Lithuania. The union was run largely by the nobility through the system of central parliament and local assemblies, but was headed by elected kings. The formal rule of the nobility, who were proportionally more numerous than in other European countries, constituted an early democratic system (“a sophisticated noble democracy”), in contrast to the absolute monarchies prevalent at that time in the rest of Europe. The beginning of the Commonwealth coincided with a period in Polish history when great political power was attained and advancements in civilization and prosperity took place. The Polish–Lithuanian Union became an influential participant in European affairs and a vital cultural entity that spread Western culture (with Polish characteristics) eastward. In the second half of the 16th century and the first half of the 17th century, the Commonwealth was one of the largest and most populous states in contemporary Europe, with an area approaching one million square kilometres and a population of about ten million. Its economy was dominated by export-focused agriculture.