Excerpts from Books and Wikipedia
"The first caliphate, the Rashidun Caliphate, was established immediately after Muhammad's death in 632. The four Rashidun caliphs, who directly succeeded Muhammad as leaders of the Muslim community, were chosen through shura, a process of community consultation that some consider to be an early form of Islamic democracy. The fourth caliph, Ali, who, unlike the prior three, was from the same clan as Muhammad (Banu Hashim), is considered by Shia Muslims to be the first rightful caliph and Imam after Muhammad. Ali reigned during the First Fitna (656–661), a civil war between supporters of Ali and supporters of the assassinated previous caliph, Uthman, from Banu Umayya, as well as rebels in Egypt; the war led to the establishment of the Umayyad Caliphate under Muawiyah I in 661." [Wikipedia]