The original combat "tank" was born out of the fighting that was World War 1. However, these were hardly representative of the vehicles that we know today to be "Main Battle Tanks". Within time, the "lozenge-shaped" vehicles of the First World War evolved to include cannon armament fitted to traversing turrets (the French FT-17 being a prime example) and less crew to manage the various required functions of the vehicle. It was not until World War 2 that armored warfare truly came into its own, beginning an "arms race" of sorts concerning tanks between world powers that ultimately produced the excellent Soviet T-34 Medium Tank and German Panther series as well as the notable American M4 Sherman and, ultimately, the late-war American M26 Pershing and British Centurion tanks. However, it was the Centurion that truly laid the foundation for the "main battle tank" category, ultimately being responsible for doing away with specifically-built tanks in the light, medium and heavy weight range classes. The MBT could now accomplish all of what was required in preceding designs.
The Centurion went on to become a post-war success story which saw thousands built and included various derivatives. By the time of the 1960s, there was a technological change in the wind and this produced the impressive Chieftain MBT for the British Army. The Chieftain became another excellent British tank design and this form mounted a reliable multi-fueled engine as well as a powerful and highly accurate 120mm main gun. If the Chieftain held any limitations it was in her engine which was never able to fully realize her output. Regardless, the Chieftain proved the most powerful tank of her time - a tremendous blend of armor and firepower at the cost of speed - that is until seated by the equally excellent German Leopard 2.
Iran became the largest foreign operator of the Chieftain and received over 700 examples. Through an agreement with the British, work then began on an "improved" Chieftain for the Iranian Army to be known by the name of "Shir 1" and 125 of these were under order. The type would serve as an interim MBT for the Iranian government commissioned the British to design and develop an all-new MBT to take on the name of "Shir 2". The Iranians committed to the purchase of 1,225 such vehicles and development ensued. However, with the fall of the Iranian government due to the 1979 Islamic Revolution, all contracts with Western powers were cancelled and this included both the Shir 1 and Shir 2 initiatives.
Rather than be left "holding the bag", British authorities quickly inked a deal with the Jordanian Royal Army to receive a modified form of the Shir 1 which had already entered production. This became the "Khalid" MBT and deliveries began in the early 1980s. Key to these vehicles was the addition of a Perkins diesel engine in a slightly raised engine compartment as well as internal revisions to suit Jordanian military tastes. The fire control system was revamped and the tank - more or less - became a more advanced, late model form of the original Chieftain series.
The next British main battle tank was to be forged from an agreement between the governments of Britain and West Germany. However, this initiative came to naught in March of 1977 and spurred the indigenous development of a new British tank under the designation of "MBT-80" (the Germans went on to introduce their Leopard 2 a short time later). Despite the promising nature of such a program, British authorities cancelled the MBT-80 endeavor for its growing developmental costs and delayed service entry window.
With the loss of the Iranian Shir 2 contract and the abandonment of the MBT-80, it was decided to continue development of a new tank based on the existing Shir 2 to replace the aging Chieftain line. Several steps were taken to modify the already evolved design for service in the European Theater (as opposed to the Middle East) and the powerful 120mm main gun was retained for its inherent value in defeating enemy armor of all known types. Key to the development of the new British tank was the introduction of "Chobham" armor - a new, highly secret (even o this day) composite armor treatment developed back in the 1960s. The armor received its name from the MoD development center at Chobham Common in Surrey and proved highly efficient in defeating or retarding the effects of shaped charge warheads as well as kinetic energy penetrators. The invention would go on to become a revolutionary addition to the combat tank as a whole with several upcoming MBT systems utilizing the technology in their design.
The Shir 2 development (now known as the "Cheviot") became a conventionally-arranged modern MBT system with a crew of four, a centrally-located turret housing the main armament and a rear-set engine compartment. Running gear straddled the hull sides with protection by way of armor "skirts". The end result promised an upgrade to the existing Chieftain line and - after formal trials and evaluation - the tank emerged as the "Challenger" Main Battle Tank - the newest British Army tank system. The British government commissioned the Royal Ordnance Factory, Leeds to produce the type through an order of 237 vehicles which was then raised to 319. It should be mentioned that the Challenger name initially served a World War 2 "cruiser" tank development though since retired.
Outwardly, the Challenger certainly looked the part of modern main battle tank. The system was crewed by four personnel made up of the driver, commander, gunner and loader. The driver managed his position at the front-center of the hull while the remaining crew took positions in the turret. The gunner was seated at the front right of the turret with the commander directly behind. The loader was to their right and managed the ammunition and main gun breech via commands from the commander and gunner as needed. The tank sported a very shallow hull structure which made for a lower profiled target. The glacis plate was well sloped, nearly horizontal in its design, while the hull roof was relatively flat - only raised at the rear due to the Perkins powerplant. The running gear consisted of six double-tired road wheels with the drive sprocket at the rear and the track idler at the front. The track system was protected overhead by the included fenders and along the side by skirt armor - a common practice in tanks since World War 2. The turret was well sloped with sharp lines for excellent ballistics protection as well as a slimmer side profile. The overhang at the rear allowed for external stowage of goods and supplies while, internally, it supplied stowage for ammunition.
The commander managed his vehicle from his turret position and had ample viewing through no fewer than nine periscopes at his station allowing for all-around views of the surrounding action. His cupola was fitted with a day sight (or night vision image intensifier) as well as an anti-aircraft machine gun (optional). His primary role was in management of his crew through the thick of action, staying in constant contact with accompanying vehicles and superiors while providing orders to the driver and gunner. As the commander went, so too did the crew and collectively they could represent a very lethal fighting force.
The driver's position at the front-center of the hull allowed for a unique perspective on the action. His position was such that he was reclined during combat travel with the hatch buttoned. There was some comfort found during "relaxed" travel when he could drive with his head out of the hatch. The hatch folded forwards onto the glacis plate and represented his primary entry/exit. However, in the event of an emergency, the driver could also make his way to the attached fighting compartment and exit the vehicle through one of the turret roof hatches as needed. Tanker drivers were well-trained professionals that, when given the freedom, could operate their 68 ton vehicles as if streamlined Cadillacs.
The gunner's station held the Tank Laser Sight which allowed for magnification or targets and, thusly, improved accuracy at range. The main gun was also stabilized along two axis and a digital fire control system allowed for firing on the move. The included laser rangefinder could "reach" targets out to 11,000 yards. Ultimately, Challengers made use of the Thermal Observation and Gunnery Sight (TOGS) which allowed for separate target output for both the commander and gunner.
The Challenger was equipped with the proven and excellent L11A5 120mm rifled main gun which was afforded 64 rounds of various ammunition types including various armor-defeating, smoke and practice rounds (separate charge and ammunition). The barrel was fitted with a thermal sleeve as well as an integrated fume extractor. A muzzle reference system was fitted at the extreme end of the barrel. A typical combat ammunition load consisted of 20 finned sabot rounds and 44 High-Explosive Squash Head (HESH) projectiles. As standard on all combat tanks, a coaxial machine gun of 7.62mm L8A2 caliber was fitted alongside the main gun in the turret and operated by the gunner. An optional 7.62mm L37A2 machine gun could be affixed to the commander's cupola for engagement of enemy infantry or low-flying aircraft. Ten electrically-operated smoke grenade dischargers were set in two banks of five launchers to either side of the turret-front. 4,000 rounds of 7.62mm ammunition were carried for the machine guns.
The Challenger was powered by a single Perkins Engines Condor CV12 V-12 diesel engine developing 1,200 horsepower. This supplied the vehicle with a top road speed of 35 miles per hour with an operational range equal to 250 miles. Cross-country traversal was deemed excellent thanks to the Hydrogas (hydropneumatic) suspension system. The powerpack alone weighed in at 5.5 tonnes but it was designed in such a way as to be removed relatively quickly for service or replacement in the field. However, the weight of the installation proved too heavy for then-modern engineering vehicles of the British Army so a new vehicle - this based on the Chieftain chassis - was developed and ultimately produced to service Challengers in the field. The same 1,200 Perkins engine was utilized in the Khalid MBT sent to Jordan.
Initial Challenger Mk 1 production vehicles were received in March of 1983 and these were delivered to British Army groups in West Germany as a deterrent from Soviet invasion through East Germany. Some five regiments were equipped with the very capable tank in the theater.
The Challenger saw deployment to the Middle East in the 1990 build up to Operation Desert Storm in 1991. Iraqi leader Saddam Hussein rolled his army into neighboring Kuwait attempting to seize a good portion of the region's oil reserves. The West, relying on the reserves, moved in to action through a coalition of forces from multiple countries in Europe and the Middle East. British Challenger systems then went to war in the ground conflict that followed a relentless air bombing campaign. Challengers acquitted themselves quite well in the action and were credited with destroying some 300 enemy vehicles without loss to a single Challenger unit. 180 total Challengers were fielded in the conflict. The 120mm main gun and stout Chobham armor design proved its worth and solidified the Challenger as one of the finest tanks in service. The war also became a proving ground for another MBT of note - the American M1 Abrams which was one of the few other tanks known to be protected in Chobham armor. If the Challenger held any limitations it was in her fire control system (FCS) which made for slow, yet steady, rates-of-fire from the 120mm main gun. This point was driven home in the Canadian Army Trophy gunnery competition where the Challenger - thought very accurate - arrived in last place in terms of rate-of-fire. This poor quality was eventually rectified in the upcoming Challenger 2 MBT series.
British Challengers were also fielded in the United Nations effort in Bosnia and Herzegovina.
Initial Challenger production marks were the Mk 1 and these were fielded without the TOGS device. The Mk 2 model included TOGS while the interior was refined to produce the Mk 3 line. The Mk 4 variant became the definitive Challenger mark. The Challenger tank chassis also served to create the modified line of command tanks in the Challenger 1 Control (brigade) and Challenger 1 Command (squadron). There was also an Armored Repair and Recovery Vehicle (ARRV) developed.
While the Challenger was entrenching itself in the British inventory, the type still shown room for improvement and a new British Army requirement was enacted to complement the type in service. Proposals ultimately included the American M1 Abrams, German Leopard 2 and French Leclerc tanks as well as a new design from Vickers (Royal Ordnance Factory, Leeds was eventually acquired by Vickers Defense Systems in 1986). To keep the British Army MBT an indigenous product, the Vickers design won out and this was eventually adopted as the "Challenger 2" which, in turn, made the original Challenger design the "Challenger 1". Instead of complementing the Challenger 1, it was later decided to outright replace the line with ex-British refurbished Challenger 1s sent to Jordan. The Challenger 2 remains the standard British Army main battle tank today and has proven equally excellent in its own right.
In all, 420 Challenger 1 tanks were produced through 1990. Jordan eventually received a total of 392 Challenger 1 tanks and knew these as the Al-Hussein and these are currently being upgraded to include updates from the Challenger 2 series. The Challenger 1 hull served as the basis of the "Challenger Marksman" system, a self-propelled anti-aircraft gun platform fitted with the Marksman turret mounting 2 x autocannons. As with the Chieftain tanks before them, the Challenger 1 tanks could also fit a dozer blade or mine clearing equipment to existing hulls for broadened battlefield roles. A trainer version with a fixed turret was also developed for driving training.
Due to the arrival of the Challenger 2, the Challenger 1 started removal from frontline service with the British Army in 1996, finishing up in 2000. Jordan remains the only foreign operator of the Challenger 1.