After Amir al-Mu’minin Ali (alayhi as-salam), the Shia gave their Baya’a (pledge of allegiance) to Imam al-Hasan (alayhi as-salam). Unlike his father, Imam al-Hasan (as) lacked experience, and Muawiya, who was extremely cunning and treacherous, exploited this weakness. He bribed various commanders, tribes, and supporters of Imam al-Hasan (as), creating divisions within his ranks.
Following a series of skirmishes and an unsuccessful assassination attempt, carried out by some former supporters of Imam Ali (as), during which Imam al-Hasan (as) was injured by an axe, he became seriously ill and weak. Gradually, his army dispersed, and people abandoned him.
Eventually, Imam al-Hasan (as) was forced to accept a treaty, which effectively ceded control of the land to Muawiya. While Sunnis often regard this as a Baya’a, a forced Baya’a is not valid according to Shariah, so it was more accurately a contract: Imam al-Hasan (as) agreed not to rebel, provided that Muawiya would not pass the caliphate to anyone else.
Later, Imam al-Hasan (as) was assassinated (with Poison), and when Muawiya broke the agreement by appointing his son as his successor, Imam al-Hussain (as) rebelled, leading to the tragedy of Karbala.
This is a concise summary of those events.
Wa Salam
