Events January–March January 12– After suspecting that he will be dismissed, Albrecht von Wallenstein, supreme commander of the Holy Roman Empire's Army, demands that his colonels sign a declaration of personal loyalty. January 14– France's Compagnie normande obtains a one-year monopoly on trade with the African kingdoms in Guinea. January 19– Charles IV, Duke of Lorraine abdicates in favor of his brother Nicholas II, who is only able to hold the throne for 75 days. January 24– Ferdinand II, Holy Roman Emperor, signs a classified order dismissing Albrecht von Wallenstein, the supreme commander of the Imperial Army. February 18– Emperor Ferdinand II's dismissal of Commander Wallenstein for high treason, and the order for his capture, dead or alive, is made public. February 25– Rebel Scots and Irish soldiers assassinate Bohemian military leader Albrecht von Wallenstein at Cheb. March 1 – The Russians vacate their camp, ending the Siege of Smolensk. March 4 – Belgian scientist Jan Baptist van Helmont is interrogated by the Spanish Inquisition and put under house arrest for his experiments into plant growth. March 25 – Leonard Calvert arrives in Maryland, with Jesuit missionaries Andrew White, John Altham Gravenor, and Thomas Gervase, establishing St. Mary's as the fourth permanent settlement in British North America. In this year they also establish an institution of higher learning there, which later becomes Georgetown University, the United States's oldest university. April–June April 1 – Nicholas II, Duke of Lorraine, who assumed the throne of the duchy on January 19 upon the abdication of his older brother Charles IV abdicates in favor of Charles. April 14 – The Battle of Amritsar begins in India when Mughal Empire troops attempt to eliminate the Sikh religious leader, Guru Hargobind, by attacking Amritsar. The Sikh defenders hand the Mughal invaders an unprecedented defeat. May 2 – With Albrecht Wallenstein having been eliminated, the Holy Roman Emperor Ferdinand II personally takes command of the Imperial Army. May 5 – King Charles I of England and Scotland first refers to the banner of the British Isles as the "Union Flag" in a proclamation that the flag shall not be used on any ships other than those "in our immediate Service and Pay, and none other." The term evolves into the description of the British flag as the "Union Jack". June 14 – The Treaty of Polyanovka is signed between the Polish–Lithuanian Commonwealth and the Tsardom of Russia,