Habib heavily contributed in the Battle of Karbala. He fought with the third Shia Imam, Husayn ibn Ali against the forces of Yazid, led by Umar ibn Sa'ad. Umar ibn Sa'ad was the son of Sa'ad ibn Abi Waqqas, who introduced Islam in China during the caliphate of Uthman ibn Affan. Husayn's forces were heavily outnumbered. Husayn had a grand total of 72 soldiers, as some soldiers from the opposition had joined his side through his influence. The most famous example of a person who joined Husayn's side through influence was a former soldier of Yazid called Hurr. Husayn's forces fought at least 5000 - 35000 of the enemy forces led by Umar ibn Sa'ad. Although, Husayn was given a chance to surrender himself and swear loyalty to Yazid . In Yazid era the essence of islam was lost because he was not a true muslim as he was a drunk and womenizer etc.
Husayn's army was split into 3 sections, the left flank, the right flank and the Ahl al-bayt. The Ahl al-bayt section consisted of the Banu Hashim, i.e., the clan of Hashim. The Ahl al-Bayt, in that context, referred to anyone who was from the family of Muhammad, either from himself or his cousins. Ahl al-Bayt means People of the House in Arabic. Habib was given the duty of being in charge of the left flank of Husayn's army, despite the fact that he was 70 years old. It is said in the book 'Karbala and Ashura', by Ali Husayn Jalali, that Habib killed 62 of the enemy soldiers before being taken as captive by enemy forces and later on decapitated by a commander in the enemy forces called Shimr ibn Dhil-Jawshan.He was promised a great amount of wealth from Yazid but was never given it. The Shia hold the belief that: it is not unusual for a man of who is 70 years old to kill 62 soldiers, if his faith (iman) mounts to a very high level. It is apparent that an anti-Islamic website states that Husayn sacrificed his family and companions as well as himself in the pursuit of power. This is obviously not true, because if it was power he was after he would have surrendered himself to Yazid, in exchange for many estates, a lot of promised wealth and high status. A reasonable question that arises from the statement that Husayn wanted power is, if Husayn was looking for power, why did he bring women and children with him? This proves that Husayn was never looking for power but wanted the women, children and his son Ali ibn Husayn, the only male survivor of the battle, to be witnesses to his sacrifice in order to convey the message of Islam by showing the great sacrifice of Husayn. Husayn is greatly known for his loyalty to Islam, his great sacrifice and his little concern for power by most Muslims, most notably by Shias, as well as many non-Muslims.