Who was Imam Hussain (AS) ?
Imam Hussain Ibn Ali (AS) the third Imam.
Imam Hussain ibn Ali ibn Abi Talib (AS) was born on 3rd of Shabaan, year 4 AH/626 AD, at Medina - killed on 10th of Muharram, year 61 AH/680 AD, at Karbala, in what is now southern Iraq. He was the second grandson of the Islamic prophet Muhammad (SAW), and the son of Imam Ali (AS), the first Imam. His mother was Fatimah (SA) daughter of Islamic prophet Muhammad (SAW).
Hussain ibn Ali (AS) is revered as the third Imam by most Shia Muslims. Hussain was killed in the Battle of Karbala in 680 (61AH) by Shimr Ibn Thil-Jawshan for refusing to pledge allegiance to Yazid I, the Umayyad caliph.
The anniversary of his martyrdom is called Ashura and is a day of mourning and religious observance for Shia Muslims. Revenge for Hussain's death was turned into a rallying cry that helped undermine the Umayyad caliphate and gave impetus to the rise of the Shia movement.