Complex sentence: On Gaddafi's orders, a general withdrawal was undertaken from Borkou-Ennedi-Tibesti Prefecture, beginning with Faya-Largeau, which had served as the main Libyan base during the preceding four years, which was in danger of being encircled.
Split into simpler sentences: On Gaddafi's orders, a general withdrawal was undertaken from Borkou-Ennedi-Tibesti Prefecture, beginning with Faya-Largeau. The town had served as the main Libyan base during the preceding four years, but was in danger of being encircled.