There would not have been any trouble at all if the OMAYYIDS...
There would not have been any trouble at all if the OMAYYIDS the declared enemies of Islam and the holy Prophet, had not been given the opportunity to rule over the destiny of the Muslims. The trouble started with MU'AVIAH and was perpetuated by him in the start of the OMAYYID dynasty of the assassins of the holy ones of the AHLUL-BAIT, who also murdered their own kith and kin, and were the debauchees and the drunkards who had broken the records of all kinds of licentiousness.
The first revolt against the KALIFATE of Ali unanimously set up by the people as a whole was MU'AVIAH. The Muslim world very well knows as to who MU'AVIAH was and of what caliber he was. He was the son of ABU SOFYAN the Arch-enemy of Islam, who was the causative factor behind every battle that was forced on the holy Prophet. MU'AVIAH, had gathered strength sufficient to establish his independence in Syria. Thus Ali had to meet MU'AVIAH in a battle at SIFFIN.
The treachery and the deceit with which ended this battle, is there in the history. After MU'AVIAH, Ali was force to meet the army under the command of AYSHA in the battle at BASRA, called the Battle of the Camel (JAMAL). After the battle of JAMAL, Ali had to meet the forces of the hypocrites at NAHRAVAN, in which Ali had prophesied that only none will be killed on his side and only nine will escape death, on the other side and it happened exactly so.
The godly rule of the Muslim empire, by Ali, the Vicegerent of God, was not allowed to continue beyond 40 A.H., (i.e., for about four years). THE UNIQUE POSITION OF ALI Ali's departure from this world was actually the departure of the holy Prophet, for both of them, were the personification or the manifestations of one and the same Divine Light. "I and Ali are of one and the same Divine Light". (SM).
The holy had come to conclude the apostleship and Ali was sent to inaugurate the Imamate, i.e., the serial of the divinely commissioned Guides, the Imams, himself being the First of them. Though the apostleship had concluded with the holy Prophet, the guidance from God for mankind is an ever continuous process of the divine grace which has to remain until the end of the world. God had never allowed any gap to be in the continuity of his guidance.
Prophets were sent in all parts of the world, one after another; where one Prophet was called back, another one in his place was sent as a prophet or a vicegerent or the WASI of the retiring one.