(Spanish M-107 image). The US Army needed a self-propelled vehicle equipped with a long-range gun, and that could be transported by air, since the existing fleet of vehicles were too heavy and this greatly limited its strategic use. In addition, the use of gasoline engines was beginning to be considered inefficient and dangerous, since they consumed too much fuel and were prone to catching fire in combat.(Spanish M-107 image). The first T-235 prototype presented by Pacific Car and Foundry was powered by a Continental AOI-628-3 opposed eight-cylinder, air-cooled, fuel injected gasoline engine developing 370 hp. But shortly after, a new prototype was unveiled, designated T-235E1, powered by a 405-hp General Motors 8V71T V8 diesel engine. With this engine the vehicle almost doubled its range, and finally this last prototype was chosen to be manufactured in series. The M-107 was fitted with an Allison XTG-411-2A cross-drive transmission with four forward gears and two reverse gears.(US Army’s M-107 image). Thanks to its aluminum construction, the vehicle only weighed 28.16 tons, and its pressure on the ground was very low. Its tracks were the 435mm wide T-132 and the suspension had a locking system that allowed the hull to be a very firm and stable firing base. In addition, at the rear of the hull was a huge, hydraulically actuated rear spade that dug into the ground before firing to further improve stability. The M-107 could cross 1.07 meter deep waterways without any preparation and lacked NBC protection.(Spanish M-107 image).The chassis was constructed of welded aluminum, suspension was torsion bars, and the running gear consisted of five driving wheels, the last of which acted as an idler wheel, with the sprocket positioned at the front. The crew of the vehicle consisted of 5 members, 4 of whom were seated outside next to the gun. The piece needed 13 servants to operate, so the other 8 members were in an M-548 tracked carrier along with ammunition, since the M-107 only carried two projectiles on board.(Spanish M-107 image).This vehicle mounted the 175/60mm M-113 (T-256E3) gun located directly above the hull which only housed the driver, who was located on the left, with the engine on his right. The gun was hydraulically operated and could be raised from -2º to + 65º and traversed 30º left or right. It also had a hydropneumatic recoil system but did not have a muzzle brake. Although the aiming and lifting mechanisms were servo-assisted, there was an emergency manual system to aim the gun.(Israeli M-107 image). The M-113 gun had a maximum range of 32.8 km with high explosive (HE) ammunition and with 10.50 meters in length could retract almost 1 meter when the vehicle had to move. The loading operation was mechanized due to the great weight of the projectiles, about 67 kg. A small hydraulic crane placed the projectile on the loading tile, then a power ramming introduced it into the breech for firing. The rate of fire was one shell per minute, although a well-trained crew could fire up to two.(Spanish M-107 image).The gun was extremely powerful, with an impressive muzzle velocity of 914 meters per second, but this had the drawback of a a short-life barrel. The average-life is calculated in about 400 shots, although if they were all with maximum propellant charge it could be reduced to 300. The change of the tube was carried out in about two hours. However, spent barrels could be reused after a retubing process, extending the life of the tube by another 500 or 700 shots.(Israeli M-107 image). The M-107 entered service in 1963 with the US Army and was subsequently exported to a dozen countries, including Israel, Italy, the United Kingdom, Iran and Spain. This vehicle was manufactured by three different companies in different periods. The first batches were manufactured by Pacific Car and Foundry and later production would go to FMC Corporation and Bowen-McLaughlin-York. From 1963 to 1980, 524 vehicles were delivered.(US Army’s M-107 image). This self-propelled gun was widely used by the US Army in the Vietnam War, usually in 12-piece batteries in the service of a Division or superior unit (Corp). It was mainly used to destroy enemy command and communication centers or against high-value static targets thanks to its enormous range. Later it would serve in joint units together with the 203mm M-110 self-propelled howitzer, which was the M-107 chassis with a larger and more accurate howitzer.The US Army only used the M-107 (on the image) in combat during the Vietnam War where it suffered the loss of quite a few units. Several dozen were also captured and used by the North Vietnamese Army (NVA) for several decades. In the late 70s the American M-107s were all converted to 203mm M-110s which demonstrated greater operational efficiency.(Israeli M-107 image). Israel was one of the biggest users of this vehicle, which it nicknamed “Romach” (spear). Until 1982 Israel acquired about 200 units which used with considerable success during the Yom Kippur War and the Lebanon War. In the early 1980s Israel modernized these vehicles by greatly increasing their range with the introduction of new powder and the Extended Range-Full Bore (ERFB) ammunition developed by Gerald Bull, creator of the long-range GHN-45 (GC-45) howitzer. With these improvements the M-107 was able to hit targets 50 km away.(Israeli M-107 image). After the Yom Kippur War, the Israeli Army constituted 3 Battalions (36 vehicles) equipped with low yield nuclear ammunition. These projectiles had a maximum range of about 40 km, although it is believed that there was a program to increase their range to 75 km. The M-107s were retired from service many years ago, but according to some sources, it is likely that a good number of them can be kept in storage due to the capacity to fire nuclear projectiles.In 1973 Spain received 12 M-107s (on the image) thanks to the American Military Aid program signed in the “Pact of Madrid”. These guns were framed in the Field Artillery Regiment No. 11 (RACA 11), belonging to the Division Artillery of the “Brunete” Armored Division No. 1.(Spanish M-107 image).These impressive pieces have been the longest and longest-range guns used by the Spanish Army. The twelve M-107 were distributed in the 6th, 7th and 8th batteries of the 2nd group of Artillery belonged to RACA 11.In 1988, all the Spanish M-107s (on the image) were transformed to the 203mm M-110A2 model, work carried out by the “Centro de Mantenimiento de Sistemas Acorazados”, (Maintenance Center of Armored Systems), (CMASA) of Segovia.Iran also acquired several dozen M-107s (on the image) that it used extensively in the 1980 Iran – Iraq War. Despite having completed almost half a century of life, according to the 2019 Military Balance, the Iranian Army still has 22 vehicles in service.The Royal British Army also acquired the M-107 (on the image), which was deployed in the BAOR (British Army Of the Rhine). A total of 24 guns, 12 per Regiment, served in the Commander Royal Artillery 1 (BR) Corps. More specifically in the 5th Heavy Regiment, (supporting the 4th Armored Division), and in the 32nd Heavy Regiment, (supporting the 1st Armored Division). The British M-107s were retired in the late 1980s.
