Siege of Cēsis Castle
1577 CE.
Shown on the map at 57.314°, 25.269°.
The siege of Cēsis Castle (1577) was a part of Ivan the Terrible's campaign to conquer Old Livonia. After a five-day-long bombardment, about 300 people within the castle committed mass suicide by blowing themselves up with four barrels of gunpowder. The event is regarded as one of the greatest tragedies in the war-torn Europe of the early modern period.
Text from the Wikipedia article Siege of Cēsis Castle (1577), licensed CC BY-SA 4.0.