According to rahyafte (the missionaries and converts website):Hussein ibn Ali (626-680) is the third Shia Imam (AS). He is the second son of Imam Ali (AS) and Hazrat Zahra (SA) and is known among Shias as Aba Abdallah and Sayydi al-Shuhada.
He and his brother, Hassan (AS), were imams for 11 years.
Imam Hussein (AS), who was raised by the Holy Prophet (PBUH), was present in many important scenes in the history of Islam, including the Event of Mubahala.
He was also a member of the Prophet’s (PBUH) Ahl-ul-Bayt (AS), about whom the Verse of Tathir (Verse 33 of Surah Al-Azhab) was revealed.
After the demise of the Holy Prophet (PBUH), Imam Hussein (AS) was one of those who defended Islam and Islamic values. He was present in battlefields at the age of 19 during the rule of Othman, the third Caliph. He also fought enemies during the rule of Imam Ali (AS) and Imam Hassan (AS).
After the martyrdom of Imam Hassan (AS), Imam Hussein (AS) became the Imam. In this period, Mu’awiya called himself the caliph and tried to restrict Imam Hussein (AS) and his companions.
After the death of Mu’awiya, his son Yazid replaced him. Yazid was a corrupt and immoral person. According to historical accounts, he was an alcoholic and drunk all the time. Although he called himself the caliph, he had no commitment to Islamic rules and principles. That is why Imam Hussein (AS) never accepted him as caliph.
The biggest barrier in the way of Yazid to reach his objectives was Imam Hussein (AS), so he tried to eliminate the Imam (AS). According to some historical sources, Yazid had plotted to kill Imam Hussein (AS). So Imam (AS) left the Hajj pilgrimage in Mecca and went to Iraq.
His destination was the city of Kufa, because the city’s people had sent numerous letters to him, urging him to establish Islamic rule in Kufa. However, when Yazid threatened the people of Kufa, they withdrew their support and abandoned Imam Hussein (AS) in the confrontation with Yazid.
Before reaching Kufa, Imam Hussein (AS) and his companions, numbered fewer than 100, were surrounded by thousands of Yazid forces.
Then a battle took place in Karbala in which Imam Hussein (AS), his brothers, sons and companions were killed and beheaded. Their women and children were also taken prisoner.
Imam Hussein (AS), who, according to the Holy Prophet (PBUH), is a leader of the youth of Paradise, was killed by those who claimed to be followers of the Prophet (PBUH).
