Imam Hussain Mosque in Kerbala. The Muslim Times has the best collection of articles to overcome sectarianism among the Muslims

Husayn Imam of Muslims
Shrine of Imam Husayn ibn Ali.
Native name	الحسين ابن علي
Born	10 October 625 (3 Sha’aban AH 4)[1] Medinah, Hijaz
Died	10 October 680 (aged 55) (10 Muharram AH 61) Karbala, Umayyad section of Mesopotamia
Cause of death	Beheaded at the Battle of Karbala
Resting place	His shrine at Karbala, Karbala Governorate, Iraq 32°36′59″N 44°1′56.29″E
Residence	Medinah, Hejaz
Known for	being a grandson of the Islamic Prophet Muhammad, the Battle of Karbala, Shi’ite Imam
Title	List[show]
Term	AC 670–680
Predecessor	(As Shi’ite Imam) Hasan ibn Ali
Successor	(As Shi’ite Imam) Ali Zayn al-Abidin
Opponent(s)	Yazid ibn Muawiyah
Spouse(s)	Shahr Banu bint Yazdegerd III(last Sassanid Emperor of Persia) Umme Rubāb Umme Laylā
Children	List[show] [7]
Parents	Ali (father) Fatimah (mother)
Relatives	Family tree of Husayn ibn Ali List[show]

Al-Ḥusayn ibn Ali ibn Abi Talib (Arabic: الحسين ابن علي ابن أبي طالب‎‎; 10 October 625 – 10 October 680) (3 Sha’aban AH 4 (in the ancient (intercalated) Arabic calendar) – 10 Muharram AH 61) (his name is also transliterated as Husayn ibn ‘Alī, Husain, Hussainand Hussein), was a grandson of the Islamic Nabi (Arabic: نَـبِي‎, Prophet) Muhammad, and son of Ali ibn Abi Talib (the first Shia Imamand the fourth Rashid caliph of Sunni Islam), and Muhammad’s daughter, Fatimah. He is an important figure in Islam as he was a member of the Bayṫ (Arabic: بَـيـت‎, Household) of Muhammad, and Ahl al-Kisā’ (Arabic: أَهـل الـكِـسَـاء‎, People of the Cloak), as well as being the third Shia Imam.

Husayn ibn Ali became the Imam of Shia Islam after the death of his older brother, Hasan ibn Ali, in AD 670 (AH 50). His father’s supporters (Arabic: شِـيـعَـة عَـلِي‎, Shī’aṫ ‘Alī) in Kufah gave their allegiance to him. However, he told them he was still bound to the peace treaty between Hasan and Muawiyah I and they should wait until Muawiyah’s death. Later, Husayn did not accept the request of Muawiyah for the succession of his son, Yazid I, and considered this action a breach of the Hasan–Muawiya treaty.^[8]

When Muawiyah died in 680 AD, Husayn refused to pledge allegiance to Yazid, who had just been appointed as Umayyad caliph by Muawiyah. He insisted on his legitimacy based on his own special position as a direct descendant of Muhammad and his legitimate legatees. As a consequence, he left Medina, his hometown, to take refuge in Mecca in AH 60.^[8][9] There, the people of Kufah sent letters to him, asking his help and pledging their allegiance to him. So he traveled towards Kufah,^[8] but, at a place near it known as Karbala, his caravan was intercepted by Yazid’s army. He was killed and beheaded in the Battle of Karbala‘ on 10 October 680 (10th of Muḥarram (Arabic: مُـحَـرَّم‎), 61 AH) by Shimr Ibn Thil-Jawshan, along with most of his family and companions, including Husayn’s six month old son, Ali al-Asghar, with the women and children taken as prisoners.^[8][10] Anger at Husayn’s death was turned into a rallying cry that helped undermine the Umayyad caliphate‘s legitimacy, and ultimately overthrow it by the Abbasid Revolution.^[11][12]

Husayn is highly regarded by Shi’ite Muslims for refusing to pledge allegiance to Yazid,^[13] the Umayyad caliph, because he considered the rule of the Umayyads unjust.^[13] The annual memorial for him and his children, family and his companions is the first month in the Islamic calendar, that is Muharram, and the day he was martyred is the Ashura (tenth day of Muharram, a day of mourning for Shi’i Muslims). His action at Karbala fueled the later Shi’ite movements.^[12]