The 31 March Incident () was a 1909 rebellion of reactionaries in Constantinople against the restoration of the constitutional system that had taken place in 1908. It took place on 13 April 1909 (31 March on the Rumi calendar in use at the time in Turkey for official timekeeping). The countercoup had attempted to put an end to the nascent Second Constitutional Era in the Ottoman Empire and to the newly established influence of the Committee of Union and Progress, in order to re-affirm the position of the Sultan Abdul Hamid II as absolute monarch.