Abdullah Öcalan actively led the Kurdish liberation struggle as the head of the PKK from its foundation in 1978 until his abduction on 15th February 1999. He is a leading strategist and the most important political representative of the Kurdish freedom movement. While under isolation conditions at Imrali Island Prison, he authored several books that revolutionised Kurdish politics, including The Political Thought of Abdullah Öcalan, Beyond State, Power, and Violence, and The Sociology of Freedom.