port, northeastern Libya. It was the site of Antipyrgos, an ancient Greek agricultural colony, and thereafter of a Roman fortress guarding the Cyrenaican frontier. The town later became a way station on the coastal caravan route. Because it is Libya's only natural harbour, Tobruk was occupied by the Italians as early as 1911 and was subsequently used as a naval and air base for their military operations to the south.

During World War II Tobruk changed hands several times and was the focus of some of the most prolonged fighting in the North African theatre of operations. The British captured the port from the Italians in January 1941, taking 25,000 prisoners in the process. The British were then forced by the Germans to withdraw to the east, leaving Tobruk an isolated British garrison that was periodically besieged by the Germans (March 1941–June 1942) when the Germans captured the city, taking about 35,000 Allied troops prisoner and capturing immense quantities of matériel. The British finally recaptured Tobruk on Nov. 13, 1942, after their Al-Alamein offensive.

Tobruk was subsequently rebuilt and became the residence of Libya's former king, Idris. It was expanded in the 1960s by the building of Marsā al-Ḥarīqah (Marsa al-Hariga), a port terminal linked by pipeline to the Sarir oil field, 320 miles (515 km) south. The British base at Al-ʿAdam to the south was evacuated in 1970. British, French, and German war cemeteries are nearby. Tobruk lies on a coastal highway that connects Tripoli with Banghāzī and Cairo. Pop. (2003 est.) 114,680.