5 Things You May Not Know GM Built For The US Military

There are a lot of interesting facts about General Motors that might surprise even the biggest car enthusiast, including being proficient with producing weapons, aircraft, and ammunition just as well as it manufactures civilian cars. The company and its many divisions have a record for assisting the United States military in one capacity or another with nearly every major conflict it has been involved with since World War I. It's not surprising to learn that Chevrolet built its popular Suburban SUV for the U.S. Army in World War II or that the Army used Cadillacs for staff vehicles during the First World War. Military personnel, after all, have to drive something even when they're away from home.

General Motors and its many divisions over the years didn't simply supply vehicles or build cars for the military. It built some of the most reputable vehicles used on land, air, and sea, as well as engines during some of the biggest conflicts the country participated in. It's not done fulfilling military contracts either. As recently as 2020, GM Defense was awarded a $214.3 million contract to build the Infantry Squad Vehicle (ISV), a fast and agile vehicle that can transport nine troops across the battlefield at a time. You might be surprised just how much GM was involved in the war effort and which vehicles it built for the military. It's not just the Humvee.

It's not unheard of for automakers to provide engines for world militaries. BMW and Aston Martin made engines during World War II. General Motors and its numerous divisions, including Cadillac and Buick, built several engines for the U.S. military during World War I. When it came to land vehicles, Cadillac built over 1,000 artillery tractor V8 engines.

For aircraft, Buick and Cadillac worked together to make the 12-cylinder Liberty aircraft engine. GM was once again pulled into the war effort when WWII started, with Buick giving a helping hand to build the Pratt & Whitney engines that went into the B-24 Liberator. Between 1952 and 1957, Buick manufactured the J65 Turbo Jet engine alongside Wright Aeronautical. The engine went into the USAF's Martin B-57B Canberra among other planes. The engine is capable of 7,200 pounds of static thrust.

Detroit Diesel Allison's engines have been installed on several U.S. military vehicles since the '90s, including light armored vehicles (LAVs) used by the Marine Corps, the Sea Fox fast patrol boat used by the Navy, and the Army's Abrams Main Battle Tank. GM also produced several gas turbine engines for multiple helicopters utilized by the Army.

The U.S. military heavily employed the amphibious DUKW truck in World War II to ferry ammunition and other equipment from supply ships on the water to personnel on land. It was the perfect vehicle for such a task, and GMC manufactured over 21,000 of them throughout the war. It was based on the automaker's six-wheel drive, 2 1/2-ton trucks. While it was aptly called a "duck" by everyone, the official "DUKW" name is actually a manufacturer's code, with every letter having a meaning. "D" was for the model year 1942, "U" referred to its amphibious body style, "K" meant it was all-wheel drive, and "W" was for its dual rear axles. The British were given roughly 2,000 DUKW's to use.

It first saw action during the Sicily invasion in 1943 and went on to be a vital utility vehicle in 1944 during the invasion of Normandy, where roughly 2,000 DUKWs brought supplies ashore. The U.S. Marine Corps got extensive use of the DUKW in the Pacific, carrying up to five tons of equipment, 25 individuals plus the driver, or a combination. The amphibious truck only traveled 6.4 mph, or 5.5 knots, on the water, while its land speed was closer to 50 mph. Years after the war, a project engineer with the Army's Amphibious Warfare Program managed to modify one and get it up to around 30 knots on the water.

Prior to World War II, General Motors didn't manufacture much for the U.S. military beyond engines, trucks, and one airplane. That changed when WWII erupted. President Franklin Roosevelt appointed the GM President to lead the National Defense Program. Every one of GM's plants was converted to create war-related materials, some of which were tanks. 

Between 1942 and 1944, Cadillac built M5 and M24 Chaffee light tanks. Thousands of them. The M5 Stuart Tank was only lightly armored. Coupled with its 37mm main gun, it served better for troop support and reconnaissance missions but couldn't do much in a face-to-face fight against Germany's tanks. The M24 wasn't much better against German tanks, but its 75mm main gun gave it a better chance than the M5. It primarily took out enemy bunkers and buildings. 

If GM made any tanks that could go head-to-dead directly with Germany's tanks, it was Buick's M18 Hellcat, a tank destroyer. If not Buick's tank destroyer, Fisher Body worked overtime and built roughly 18,000 tanks and tank destroyers. Amongst these were the M4 Sherman and M26 Pershing tanks, as well as the M10 and M36 tank destroyers.

Aside from the 12-cylinder Liberty aircraft engines General Motors manufactured in World War I, the Aeroplane Division of GM's Fisher Body also built around 1,600 DeHavilland DH-4 planes. GM was one of three manufacturers to build the bi-plane for the U.S. Army Air Service. The other two were the Dayton-Wright Company and the Standard Aircraft Corporation, with Dayton-Wright building the bulk of the Army's order (3,106 DH-4s). Unlike the British version that used a Rolls Royce engine, America's used the American Liberty 12-cylinder engine. It was the only American-built plane to see combat during the war and stuck around until 1932.

GM played a significant role in making some of the most prolific airplanes America used in World War II. General Motors' North American Aviation Division built P-51 Mustangs, B-25 Mitchell bombers, as well as AT-6 training planes. It wasn't components for the planes or just a couple dozen, either. GM built thousands of them. The P-51 Mustang dominated the skies over Europe, out-maneuvering Germany's Messerschmitt Bf 109. The B-25 bomber is famously known for its involvement in the Doolittle Raid where it was one of the most unexpected planes to land on an aircraft carrier. Fisher Body also built components for the B-25 as well as the B-17 Flying Fortress and B-29 Superfortress.

General Motors and its various divisions were busy during WWII fulfilling defense contracts. It didn't produce a single civilian vehicle from any of its 100 plants between 1942 and 1945, instead delivering over $12 billion worth of war products. Those products included 15 different types of anti-aircraft guns, cannons, carbines, artillery shells, and the .30 Caliber Browning machine gun. Years later, during the Korean War, Oldsmobile was tasked with making ammunition for bazookas and anti-aircraft guns. It made over eight million bazooka shells and 5,431 AA guns.

One of the most reputable rifles used by the U.S. military during the Vietnam War was the M16. Unfortunately, early production models were loathed by troops on the ground because it would commonly jam or not function properly due to Vietnam's environmental conditions. It was bad enough that soldiers preferred the heavier M14. So, the Department of Defense demanded modifications be made to the weapon, including a chrome-plated chamber to prevent rust, better powder, and a 30-round magazine rather than the old 20-rounder. The Defense Department awarded the contract to GM's Hydra-Matic division, designating the modified version the M16A1.

Hydra-Matic quickly became the biggest producer of the rifle, delivering 100,000 units by 1969, and before the end of the war, it manufactured nearly half a million of them. During the same period of time, GM manufactured the M39 A3 20mm cannon that was used on several fighter jets of the era, including the F-100 Super Sabre, the world's first supersonic fighter jet, and the F-5 Tiger.