The battle saw the armies of Yazid face those of Imam Husayn. The armies of Yazid prevailed, and ended the threat to his claim over the caliphate from Husayn, but not before Husayn and his entire family were killed.
The body of Husayn was decapitated, and the head was brought back to Yazid.
The day is remembered by Muslims as Ashura, and is extremely important to the Shia. Yazid's actions in regards to Husayn and the battle have made him a notorious figure.