Background

     The Order of the Teutonic Knights was formed in Palestine during the Third Crusade in the 12th century. After the defeat of the Christians in the Middle East, the Order moved to central Europe to Transylvania. In 1230, Grand Master Hermann von Salza was invited by the Polish Duke Konrad I of Masovia to help Christianize the Baltic Old Prussians that continually harassed villages in Masovia (Mazowsze). This was a fatal mistake because the Order then created the independent Monastic State of the Teutonic Knights in the conquered territory, and built the huge castle of Marienburg (Malbork in Polish). Subsequently they attacked the pagan Lithuanians as well as Polish Pomerania and Kujawy.

     In Poland the last of the Piast kings of Poland, Casimir III the Great, died childless in 1370. The throne was given to the husband of Casimir's sister Elizabeth, Louis I of Hungary. When Louis died, the Polish magnates elected his youngest daughter Jadwiga as Polish sovereign. In 1384 she was crowned as KING (there was no provision in Polish law for a reigning queen) at the age of 10. She was already well educated and spoke several languages.

     In the meantime the Knights continued to attack Lithuania and established a stronghold in Livonia (present day Riga). Both Poles and Lithuanians sought an alliance to fight off the German threat. In August 1385, at the castle of Kreva (currently in Bialorus), Grand Duke Jogaila signed an agreement to bring western Christianity to all Lithuanians, to restore to Poland regions that had been lost earlier, and to attach Lithuania to Poland in a personal alliance.
In February 1386 he was baptized in Cracow's Wawel cathedral. Two weeks later he married Jadwiga and was crowned king of Poland with the name Władysław Jagiełło. Mass baptisms of Lithuanian nobles and people were performed during the following years.
In 1387, Queen Jadwiga personally led two military campaigns to reclaim the province Red Ruthenia (present day western Ukraine), which had been occupied by Hungary. In 1389 she died as a result of complications in childbirth (the child also died). Subsequently Jagiełło married Anna of Celje, granddaughter of Casimir III.

The Christianization of Lithuania removed any justification for "conversion" campaigns by the Teutonic Knights. Regardless, they continued their attacks, taking advantage of disputes between various Dukes of Lithuania, and Lithuanian wars in the east against the Mongols, to occupy a large area along the Baltic coast.
Finally in 1409 Grand Duke Vytautas assembled an army of Lithuanians, Tartars and even some Russians, and joined the Polish king's army in a campaign against the Knights. The combined forces were successful in the great Battle of Grunwald and destroyed the entire Teutonic army. This removed the German threat for the next 300 years.

Aftermath

     The resulting union of Poland and Lithuania created the largest country in Europe of the 15th century, stretching from the Baltic to the Black Sea and encompassing all of present day Latvia, Bialorus, Ukraine and a part of north-western Russia. This was the Golden Age of Poland.
Throughout Poland and Lithuania great palaces, cathedrals and schools were built, towns thrived. Even in smaller towns building activity and prosperity resulted. In the Biega home town of Mrzygłód a church was built using German prisoners of war. It still exists today and will be celebrating its 600th anniversary this fall.

Almost every town in Poland has Grunwald and Jagiełło monuments. Needless to say, they were all destroyed during the Nazi occupation of Poland in World War II. After the war they were recreated from photographs. The largest of them, shown above, is located in Cracow.
A statue of King Wladyslaw Jagiello stands in Central Park, close to he Metropolitan Museum. It was presented to New York in 1939 after the World's Fair.

     NOTE: In World War I, in 1915, another Battle of Tannenberg took place close by. The German army almost completely destroyed the Russian army, leading to the revolution of 1917 and the rise of the Soviet Union.
In World War II, a failed attempt to assassinate Adolf Hitler occurred close by, in the bunker of Hitler's command post.