Sayyiduna Ali (radi Allahu anhu) was the son of Abu Taalib, an uncle of Sayyiduna Rasulullah (sallal laahu alaihi wasallam). Sayyiduna Ali (radi Allahu anhu) was married to Sayyadah Bibi Fathima (radi Allahu anha), the daughter of Sayyiduna Rasulullah (sallal laahu alaihi wasallam). They had 3 sons, Sayyiduna Hassan, Sayyiduna Hussain and Sayyiduna Mohsin (radi Allahu anhumul ajma'in).
Sayyiduna Ali (radi Allahu anhu) took part in the battle of Badr, Khandaq and Khaibar. At Khaibar, it was Sayyiduna Ali (radi Allahu anhu) who subdued the Jews with his furious assault. He also held many important positions during the time of Sayyiduna Rasulullah (sallal laahu alaihi wasallam) and the first 3 Caliphs before him.
The situation in Madinatul Munawwarah after the murder (Shahaadah) of Sayyiduna 'Uthman (radi Allahu anhu) was serious. Sayyiduna Ali (radi Allahu anhu's) first task was to rid Madinatul Munawwarah of the rebels and to return the situation to normal.
Sayyiduna Ali (radi Allahu anhu) was able to force the rebels to withdraw from Madinatul Munawwarah and to establish peace and order in the city. The powerful governor of Syria, Sayyiduna Mu'awiyah (radi Allahu anhu), challenged Sayyiduna Ali (radi Allahu anhu) and refused to pay homage to him. Sayyiduna Mu'awiyah (radi Allahu anhu) insisted that Sayyiduna Ali (radi Allahu anhu) arrest the murderers of Sayyiduna 'Uthman (radi Allahu anhu) and hand them over to him.
Another serious development took place. Sayyadah Aishah (radi Allahu anha) and two leading Sahaba, Sayyiduna Talha and Sayyiduna Zubair (radi Allahu anhuma) declared their opposition to the Khilaafat of Sayyiduna Ali (radi Allahu anhu). They left Madinatul Munawwarah for Makkatul Mukarramah and from there travelled to Basrah where they rallied men and new supporters.
On the 17th of July 659 A.C., Sayyiduna Ali (radi Allahu anhu) overcame the Khaarijees in a battle near Nahrawan, in which, it is said, that 40 000 lives were lost.
Sayyiduna Ali (radi allahu anhu) lived a simple life. He refused any luxury food and wore simple clothes thinking of the poor. He should sleep on the ground and even sit on the floor. He repaired his own clothes and shoes and even did manual labour. He spent nights in Salaah and should fast for three days in a row. Honesty, piety, justice and love of truth were the main marks of his character.