Complex sentence: The fall of the last remaining cities under pro-Gaddafi control and Sirte's capture on 20 October 2011, which culminated with the killing of Gaddafi, marked the end of the Libyan Arab Jamahiriya regime.
Split into simpler sentences: The fall of the last remaining cities under pro-Gaddafi control and Sirte's capture on 20 October 2011. This culminated with the killing of Gaddafi and marked the end of the Libyan Arab Jamahiriya regime.