From BiblePortal Wikipedia

Hossein [1]

the second son of Ali and Fatima, and the third of the twelve Imams, was born A.D. 625. He endeavored to dissuade his brother Hassan (q.v.) from resigning the caliphate in favor of Moawiyah, but on finding his remonstrances unavailing, he entered heartily into the support of the new caliph, and even served in his army when the Saracens first attacked Constantinople. On the death of Moawiyah, in 679, his son Yezid succeeded, but Hossein contested the caliphate with him, having been deceived by the promise of powerful support from the professed adherents of the house of Ali. Overpowered by numbers, and deserted by many of his followers, he fell by the hand of one of Yezid's soldiers, on the 10th of the Mohammedan month Mohanem, A.D. 680. A splendid mosque was erected over the place of his burial. The place, which was named Meshed Hossein (the place of Hossein's martyrdom), is a favorite resort of pilgrims to this day.