The Young Turk Revolution was a constitutionalist revolution in the Ottoman Empire. Revolutionaries belonging to the Internal Committee of Union and Progress (CUP), an organization of the Young Turks movement, forced Sultan Abdul Hamid II to restore the Constitution, recall the parliament, and schedule an election. Thus began the Second Constitutional Era which lasted from 1908–1912 and also the Turkish Revolution, an era of political instability and social change which lasted for more than four decades.