aug 23, 661 - Hasan–Muawiya treaty
Description:
Following Ali's murder, Hasan ibn Ali attained to the caliphate. To avoid the agonies of a further civil war, Hasan signed the Hasan–Muawiya treaty with Muawiyah. According to the treaty, Hasan ceded the caliphate to Muawiyah but the latter could name no successor during his reign; instead, he was to let the Islamic world choose its successor afterward.
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