Complex sentence: In August, Goukouni was arrested by the Libyans, which spurred his troops to attack Libyan positions in the Tibesti, forcing their withdrawal from the mountains, and in October the remnant GUNT forces pledged themselves to Habré.
Split into simpler sentences: In August, Goukouni was arrested by the Libyans, which spurred his troops to attack Libyan positions in the Tibesti, forcing their withdrawal from the mountains. In October the remnant GUNT forces pledged themselves to Habré.