In 1956 Britain and France launched a joint operation to seize the Suez Canal, only to be forced into a humiliating withdrawal under US and Soviet pressure. The lesson French planners drew was blunt: alliances could not be relied upon in an existential crisis, and France needed its own nuclear weapons under its own control. De Gaulle made the Force de frappe a centrepiece of national policy, and the fastest route to a credible deterrent was a manned bomber that could reach Soviet targets at supersonic speed. Dassault’s Mirage IV was the answer — conceived, in effect, as a nuclear delivery system with a cockpit, sized around the bomb it had to carry.

A supersonic delta burns fuel ferociously, and the Mirage IV’s unrefuelled radius was never enough to reach deep Soviet targets and return — many wartime profiles were frankly one-way. France closed the gap two ways. First, it acquired a dozen Boeing C-135F tankers, derivatives of the KC-135, delivered from 1964. Second, individual bombers carried buddy refuelling stores so one Mirage IV could top up another in flight. As Soviet surface-to-air missiles improved through the 1970s, the fleet also abandoned high-altitude penetration and re-trained to attack from very low level — screaming in at a few hundred feet to slip beneath radar, a punishing profile that drove the switch from the AN‑11 bomb to the toss-delivery-hardened AN‑22.

By the early 1980s a subsonic run-in to drop a gravity bomb over a modern target had become suicidal. Rather than retire the airframe, France rebuilt around 18–19 aircraft (sources differ) into the Mirage IVP — “P” for Pénétration — able to launch the ASMP supersonic stand-off nuclear missile from tens of kilometres out, well outside the innermost defences. The rebuilt jets became operational in 1986, with new navigation and attack systems, and kept the ageing delta strategically relevant until the airborne strike mission passed to the Mirage 2000N in the mid-1990s.

The Mirage IV was a French state strategic asset, never exported and never sold on an open market, so several figures vary between sources. Length is quoted between about 23.3 and 23.5 m; maximum speed as Mach 2.0 sustained rising to about Mach 2.2 in a dash; and range figures swing widely with mission profile — from roughly 1,200 km combat radius to well over 4,000 km ferry range with in-flight refuelling. About 62 production aircraft were built between 1964 and 1968, of which some 18–19 were later rebuilt as Mirage IVP. No credible unit cost or cost-per-flight-hour exists in open sources; treat any precise dollar figure with caution.