The Battle of Karbala (10 October 680 CE) was a small-scaled military engagement, fought near the river Euphrates, in modern-day Iraq, which saw the massacre of heavily outnumbered Alid troops under the command of Husayn ibn Ali (l. 626-680 CE and also given as Hussayn) by the army of the Umayyad Dynasty (661-750 CE). Though the battle was one-sided and ended with a decisive Umayyad victory, the fallen soldiers of the Husaynid faction, including Husayn himself have ever since been venerated as martyrs of Islam. This battle also became one of the core reasons for opposition against the Umayyads, who were overthrown around 70 years later in a bloody rebellion. Even to this day, the battle remains one of the central defining elements of Islamic heritage and is commemorated annually through the Ashura festival by Shia Muslims.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/1645/battle-of-karbala/.