Ḥasan b. ʿAlī b. ʾAbī Tālib (a) (Arabic: حسن بن علي بن ابي طالب) (b. 3/625 - d. 50/670), son of 'Ali (a) and Lady Fatima (a), is the second Imam and Caliph of Shi'a. He became caliph and imam at the age of 37. He accepted a peace treaty with Mu'awiya in 41/661 because of his responsibility of Imamate and preserving the unity of Muslims. His government lasted six months and three days. He went to Medina after the peace treaty, and stayed there until he was martyred ten years later. He was buried in the Jannat al-Baqi' cemetery. His decisions show his solemn and tolerant personality and demonstrated an example of unity at that time and as a moral and religious teaching, it greatly regulated Muslims and especially Shi'a throughout their history in their approach towards fundamental concepts like authority, war and peace.