Ali becomes the fourth caliph
Accordingly, Abu Bakr was elected at the age of 60 years, adopting the title of khilafat rasulillah (Vicegerent of the Messenger of God), a title which was soon simplified to khalifa (whence the word caliph was coined in western languages). Abu Bakr died in 13/634 after ruling for 2 years, 3 months and 10 days. He nominated Umar, whose age at that time was 52 years, ruled for 10 years, 6 months and 4 days; and died in 23/644. The third caliph Uthman was selected at the age of 70 years, who was assassinated in 35/656 after ruling for 11 years, 11 months and 14 days. Wardi writes in "Wu'az al-Salatin" (p. 217) that, "It was the Umayyads who engineered the murder of Uthman, with Muawiya instigating the murder and Marwan working out the death." Immediately after the murder of Uthman, a crowd rushed to Ali in the mosque, urging him to accept the caliphate. Eventually, Ali consented and became the fourth caliph. This implies that the temporal and spiritual powers once again joined together in Islam just 24 years, 8 month and 28 days after the death of Muhammad. Dr. Gustav Weil writes in "History of the Islamic Peoples" (New Delhi, 1914, p. 88) that, "Still from credible sources it is clear enough that Ali surpassed not only Muawiya but even Abu Bakr and Umar in his unfailing love of righteousness, in bravery and eloquence."
It can be said that Ali's succession to the caliphate was approved by the vast majority of Muslims in Medina, and also in most of the provinces of the state. He was however placed in a difficult time, and the dice of fate appears to have been loaded against him. The period of four caliphs were subdivided into four distinct periods. It falls to the lot of Ali that he should pilot the bark of Islam in times of the most dangerous internecine dissensions. To maintain a proper hold of state administration under such conditions was a difficult as to keep a boat steady on stormy waters. Nevertheless, Ali displayed a high example of affection and sympathy for brother-Muslims which is without parallel.