Imam Hassan al Mujtaba (a.s)
Imam Hassan (a.s) became the second Imam after the death of his father Imam Ali (a.s). In addition to this, he was also elected By his father and the Muslim people as the Caliph of the Muslim Ummah (population).
However, Muawiya who was responsible for killing Imam Ali (a.s) was not happy that the Imam's son became the Caliph as he wanted to be the leader of the Muslims instead. Muawiya sent Imam Hassan (a.s) letters trying to convince the Imam to give up the position of Caliph and let him lead.
However Imam Hassan (a.s) did not back down and he used the argument his father Imam Ali (a.s) used against Abu Bakr when Abu Bakr took away the leadership from him. Imam Ali (a.s) had said: "If Quraysh could claim the leadership over the Ansar on the grounds that the Prophet belonged to Quraysh, then the members of his family, who were the nearest to him in every respect, were better qualified for the leadership of the community."
In his reply, Muawiya said that that what Imam Hassan (a.s) said was true (that Imam Hassan had the right to lead), but that he could not accept the idea because he believed he would simply make a better leader than Imam Hassan (a.s) because he was older and had more experience. Instead, Muawiya suggested that he should become the leader first, and then when he dies he will let Imam Hassan (a.s) be the Caliph after him or face war. At the same time Muawiya gave a lot of money to the people in Imam Hassan's (a.s) army to make them turn against him, and this plan worked. The Imam (a.s) was left with few supporters and a very small army.
Imam Hassan (a.s) was a very noble person and he knew that if he went into war all the true followers of Ahlul Bayt would be killed and the word of God would be lost. He therefore avoided war but instead forced Muwya to sign a treaty (which involves both sides agreeing to follow a number of rules )
Imam Hassan (a.s) is therefore famous for the peace he brought to the Muslims by avoiding war with the Mawya.
The treaty Imam Hassan (a.s) forced Mawya to sign was important for two reasons:
1. It kept the followers of Ahlul Bayt (a.s) alive
2. It helped show that Muawya and his son Yazid did not follow the rules of the treaty and that Imam Hussain (a.s) had no choice but to fight Yazid in the future.
After they came to an agreement. Imam Hassan (a.s) gathered all the Muslims and explained to them what happened. He is quote as saying:
“O’People, Allah has guided you through our elders (Muhammad and ‘Ali) and spared you from bloodshed through those who followed (referring to himself). Indeed this (the Khilafat) is nothing but a passing phase, these worldly possessions keep shifting and changing hands."
This showed that Imam Hassan (a.s) did not care about having an important position in front of the people, and that he cared only about guiding people spiritually to Allah.
After this Imam Hassan (a.s) lived the rest of his life in Medina where he met with his followers and taught them how to live a good Muslim life. Imam Hassan was poisoned at the age of 47 years by Mawya and his helpers.
Imam Hassan's (a.s) position as the next caliph of the Muslims was so obvious that not even Muawiya tried to deny it. instead Muawiya argued that he would make a better leader in terms of age and experience.