On this day in 1582, Pope Gregory XIII announces the Gregorian calendar, now the world’s most widely used calendar.
On this day in 1918, Estonia declares independence from Russia.
On this day in 1920, the Nazi Party (NSDAP) is founded in the Hofbräuhaus beer hall in Munich, Germany.
On this day in 2020, Russia launches a full-scale invasion of Ukraine, six years after the annexation of Crimea.
