Harley-Davidson Military Model U
Starting in 1939, Harley-Davidson began producing the military version of the Model U motorcycle. The Model U was part of Harley's 74-cubic-inch big-twin flathead family, introduced in 1937 after the V-series and listed in the broader Riding Vintage Model Reference. Initial orders for the military version were made by the U.S. Army, and Harley added an "A" to the model designation to signify that it was being built for the Army.
The Model UA had a number of differences when compared to the original Model U made for civilians. Some of these included standard front and rear crash bars, a windscreen with a transparent upper section, and one of three types of fork-mounted holsters that could hold a Thompson submachine gun, a carbine, or a rifle. The 74-cubic-inch flathead motor was detuned to lower its compression and fitted with a larger, more restrictive air filter. The transmission gearing was also lowered to make the motorcycle more suitable for sidecar use.
The Army Model UA
The Army Model UA was not just a civilian Model U in military paint. It kept the basic big-twin flathead character of the civilian motorcycle, but the wartime equipment and sidecar-oriented setup made it a very different machine in use. The big flathead was heavy, torquey, and built around older Harley-Davidson controls: a hand-shift four-speed transmission, foot clutch, rigid rear frame, sprung saddle, and drum brakes. It was exactly the kind of machine that could do hard service, but it was not the light solo motorcycle that the U.S. Army would eventually buy in huge numbers.
For identification, the important point is that the "A" in Model UA refers to the Army version of the Model U. It is a model designation, not a separate engine family. Readers working through serial-number details can compare the model designation logic against the Riding Vintage Harley-Davidson VIN Decoder, but the equipment that made a UA a military motorcycle was not all encoded in the engine number.
U.S. Army and Navy Use
During the three years it was produced, the U.S. Army purchased 670 units. That was a small number compared with roughly 60,500 U.S. Army WLAs, with broader wartime Harley totals often quoted higher. The difference says a lot about how the Model U fit into wartime service. The UA was a big 74-cubic-inch motorcycle that made sense for sidecar work, patrol duty, and heavy service, while the WLA became the standard solo military Harley for mass production.
The U.S. Navy also purchased an unrecorded amount of Model U motorcycles for shore patrol, and these were easily distinguishable by their gray paint schemes. Period and museum references treat the Navy machines as a very limited group, which fits the larger point: the military Model U was never a volume-production wartime motorcycle in the same way the WLA was.
That limited use should not make the Model U less interesting. In some ways it makes the military U and UA machines more interesting, because they sit between two worlds: the older big-twin sidecar motorcycle and the newer wartime preference for lighter solo motorcycles and four-wheel utility vehicles, a shift Harley-Davidson explored with the experimental WAC Peep Jeep. The Model U was still a dependable, heavy-duty Harley flathead, but it was not where the bulk of wartime motorcycle production went.
South African Model U Sidecar Service
Although the U.S. Army preferred the solo Model WLA for wartime service, the South African Union Defense Forces thought the sidecar-equipped Model U motorcycles would be suitable for their motorcycle companies. Between 1940 and 1941, the Union Defense Forces ordered 1,156 Model U motorcycles, all equipped with left-hand mounted sidecars. They also ordered an additional 3,100 WL motorcycles to help fill out their three motorcycle companies.
The South African order is where the military Model U story becomes much bigger than the small U.S. Army numbers suggest. A big Harley-Davidson flathead with a sidecar was useful for hauling men, equipment, and messages over long distances, especially where roads and conditions were rough. The lowered gearing, low-compression motor, crash protection, and sidecar equipment all made more sense in that role than they did for a solo dispatch motorcycle.
The three motorcycle companies of the Union Defense Forces saw action all across Africa. After completing their training in Voortrekkerhoogte, they proceeded by ship to Mombasa. There they joined up with armored cars and began an assault against the capital of Italian East Africa. From there they continued battling into Abyssinia, modern day Ethiopia, then to the island of Madagascar and finally to the deserts of Libya and Egypt by the fall of 1942.
The conditions these motorcycles faced could be argued to be some of the worst imaginable. Riding through the arid wastes of Kenya, through torrential rain, across the mountains, and in intense heat, the Harley-Davidson Model U proved to be a dependable and durable war machine.
Model U Military Equipment and Sidecar Setup
The military Model U's equipment was practical rather than decorative. Crash bars helped protect both the motorcycle and rider. The windscreen gave the rider some shelter while keeping a transparent upper section for visibility. Fork-mounted holsters allowed the motorcycle to carry a Thompson submachine gun, carbine, or rifle depending on the fitting used. Blackout or reduced-visibility lighting, gray or military paint, and sidecar fittings gave these motorcycles a very different look from a civilian Model U.
Harley-Davidson also experimented with an armed Model U prototype.
Mechanically, the Model U was already a strong platform for sidecar use. The 74-cubic-inch flathead was not a high-speed racing motor; it was a long-stroke working engine with the kind of torque that mattered when a sidecar, rider, passenger, tools, weapons, or supplies were added. The four-speed hand-shift transmission and lowered gearing suited slow-speed pulling work better than open-road solo riding.
How the Military Model U Compared to the WLA
The easiest way to understand the military Model U is to compare it with the WLA. The WLA was the wartime Harley most people recognize: a 45-cubic-inch solo motorcycle, built in enormous numbers for dispatch, escort, patrol, and general military use. The Model U and UA were bigger, heavier, and far less common. They belonged more naturally with sidecar and shore-patrol work than with the mass-produced solo motorcycle role.
That difference explains why the Model U did not become the dominant American military Harley of World War II. It was not because the motorcycle was weak. Quite the opposite: the surviving record and the South African service history show a rugged flathead machine that could take punishment. It was simply a heavier, more specialized motorcycle at a time when military demand favored lighter solo motorcycles and practical utility vehicles.
Surviving Military Model U Motorcycles
Surviving military Model U and UA motorcycles are scarce today. Surviving examples appear in museum and private-collection contexts, including gray Navy shore-patrol machines and restored or preserved U-series sidecar outfits. Because original parts, sidecars, military fittings, and correct paint details are hard to verify, restored examples should be viewed carefully, especially when they mix military, civilian, police, WLA, or Servi-Car components.
Even so, the military Model U deserves more attention than it usually gets. It was never the mass-produced wartime legend that the WLA became, but in Army, Navy, and especially South African sidecar service, it proved that the old big-twin Harley flathead still had a place in World War II.