Battle of Grunwald (2nd Battle of Tannenburg) was fought on July 15, 1410 led by Polish King Władysław Jagiełło and Lithuanian Grand Duke Vytautas who defeated the Teutonic Ulrich von Jungingen. The Teutonics were virtually decimated, either killed or taken prisoner. Despite their defeat, the Teutonic Knights withstood the siege of their fortress in Marienburg (Malbork) and suffered minimal territorial losses at the Peace of Thorn (1411) (Toruń), with other territorial disputes continuing until the Peace of Melno in 1422. However, they would never recover their former power. War reparations became a financial burden, and inflamed internal conflicts, precipitating an economic downturn in the lands under their control. The Battle of Grunwald shifted the balance of power in Central and Eastern Europe and marked the rise of the Polish–Lithuanian Commonwealth as the dominant political and military force in the region. The battle was one of the largest in Medieval Europe and is regarded as the most important victory in the histories of Poland and Lithuania.
Henryk Arctowski, born Henryk Artzt, was a Polish scientist and explorer. Living in exile for a large part of his life, he was one of the first persons to spend the winter in Antarctica and became an internationally renowned meteorologist. He was instrumental in restoring Polish independence after the First World War. Several geographical features, the Henryk Arctowski Polish Antarctic Station and a medal of the National Academy of Sciences are named in his honor.
Henryk Zygalski (dob) was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II. He worked with Marian Rejewski and Jerzy Rozycki to develop methods and equipment for decrypting Enigma messages. In late 1938 he designed the "perforated sheets," also known as "Zygalski sheets," a manual device for finding Enigma settings. These Polish mathematicians were the first to break the Enigma Code and passed on their information to the French and British governments before the outbreak of World War Two.