Complex sentence: During the Algerian Civil War, he became head of the Department of Counter-Espionage and Internal Security (DSI), in charge of secret operations against Islamist guerrillas and counter-espionage--a post which he occupied until his death, untouched by changes of government or reshuffles.
Split into simpler sentences: During the Algerian Civil War, he became head of the Department of Counter-Espionage and Internal Security (DSI). He was in charge of secret operations against Islamist guerrillas and counter-espionage--a post which he occupied until his death, untouched by changes of government or reshuffles.