onward, 12 aircraft were also equipped to carry the CT52 reconnaissance pod in the bomb recess. These aircraft were designated Mirage IVR for reconnaissance. The CT52 was available in either BA (Basse Altitude, low-level) or HA (Haute Altitude, high-altitude) versions with three or four long-range cameras; a third configuration used an infrared line scanner. The CT52 had no digital systems, relying on older wet-film cameras. The first operational use of the system took place during missions in Chad in September 1974. During the 1980s, a total of 18 Mirage IVs were retrofitted with a centreline pylon and associated equipment to carry and launch the nuclear ASMP stand-off missile. The Mirage IVA could theoretically carry up to six large conventional bombs at the cost of drop tanks and ECM pods; such armament was rarely fitted in practice. Operational history Introduction and early operations In February 1964 deliveries of the Mirage IV to the French Air Force started, with the first French Mirage IV squadron being declared operational on 1 October that year. The Mirage IV bomber force soon consisted of nine squadrons of four aircraft (2 pairs – one aircraft carrying the nuclear bomb, one a buddy-refuelling tanker) each. When fully built up, the force consisted of three wings. These wings were each divided into three bomber squadrons, each equipped with a total of four Mirage IVs, with each deployed at a different base to minimise the potential for an enemy strike to knock out the entire bomber force. These squadrons were: 1/91 'Gascogne' based at Mont de Marsan 2/91 'Bretagne' based at Cazaux 3/91 'Beauvaisis' based at Creil 1/93 'Guyenne' based at Istres 2/93 'Cevennes' based at Orange 3/93 'Sambre' based at Cambrai 1/94 'Bourbonnais' based at Avord 2/94 'Marne' based at St-Dizier 3/94 'Arbois' based at Luxeuil After establishment of its own deterrent force, the Force de Dissuassion, more commonly known as the Force de frappe, France withdrew from the military command structure of NATO in 1966. De Gaulle viewed the operational establishment of the Mirage IV fleet, a critical component of the independent Force de frappe, as highly influential to his decision to withdraw France from NATO, and that an independent French nuclear deterrent was necessary to ensure independence as a nation. From 1964 to 1971, the Mirage IV was France's sole means of delivering nuclear ordnance. At this point they were each armed with a single 60