M8 Greyhound

The M8 began life as a wheeled tank destroyer. The US Army wanted a fast six-wheeled vehicle carrying a 37 mm gun that could find German armour and kill it, and the design that emerged from Ford in 1942 did the first half well. By the time it reached production in 1943, the second half had become fantasy: the 37 mm M6 managed about 46 mm of penetration at 914 m, against the 80 mm frontal plate of a Panzer IV Ausf. H — and the Panther was thicker again, and sloped.

Rather than cancel it, the Army changed the job. The M8 was reclassified as a light armoured car and sent to the cavalry reconnaissance units, where its speed, its radios and its quietness mattered more than its gun. The vehicle entered service under a designation that no longer mentioned tanks.

On roads it was very fast — around 89 km/h — with six-wheel drive, a low silhouette and, by armoured-vehicle standards, quiet running. A cavalry reconnaissance troop’s job is to locate the enemy, report accurately, and survive the discovery, and for that the Greyhound was close to ideal: it could get somewhere quickly, look, and be gone before the response arrived.

The British, who received numbers of them under Lend-Lease, gave it the name Greyhound for exactly that quality. The US Army never officially adopted it: its own manuals went on calling the vehicle the M8 Light Armored Car for the rest of the war.

The ~89 km/h that defines the Greyhound is a road figure, and the qualification matters more than it sounds. The M8 was a 6×6 wheeled vehicle of ~7.9 tonnes with a low belly, and in mud, deep snow or soft ground it bogged, bellied out and lost the speed that was its entire reason for existing. The sandbags the crews piled on against mines made it worse.

The consequence shows up in the unit records rather than the specifications: reconnaissance troops in the Italian winter and in the Ardennes repeatedly set their M8s aside and worked with tracked M5 Stuarts and jeeps instead, which could go where the armoured car could not.

Its notorious weakness was underneath, and the figure is what makes it concrete: the hull floor was 6.4 mm thick — a third of the 19 mm on the upper front plate — on a vehicle whose whole purpose was to drive down roads nobody had yet cleared. A mine detonating beneath an M8 was frequently fatal to the whole crew of four.

The field solution was universal and unofficial: crews lined the floor with sandbags, and often piled more on the front, accepting the weight and the loss of performance in exchange for a chance of surviving a mine. Photographs of Greyhounds in Europe show it so consistently that the sandbags look like part of the design, and no production change to the floor was ever made.

The turret was open-topped, which is the usual reconnaissance trade: excellent all-round observation and hearing, no protection from air burst, grenades or anything dropped from above. It carried the 37 mm M6 with a coaxial .30 calibre machine gun, and most vehicles added a .50 calibre on a ring mount for aircraft and for the ground work the 37 mm could not do.

Against infantry, trucks, gun positions and light vehicles that armament was entirely adequate — and those were the targets a scout car actually met. It carried 80 rounds of 37 mm, and against tanks the doctrine issued to its crews was four words: report and withdraw.

The same hull produced a second vehicle that is regularly mistaken for a stripped or damaged M8. The M20 Armored Utility Car deleted the turret entirely, leaving an open fighting compartment with a ring mount for a .50 calibre and space for passengers, radios or ammunition. It was a production type in its own right, built by Ford alongside the M8, not a conversion of casualties.

It did the work the reconnaissance squadrons needed that a turret got in the way of: troop and squadron command vehicle, liaison, carrying a forward observer, towing a light anti-tank gun. It inherited the 6.4 mm floor, and the sandbags with it.

The Greyhound first saw action in Italy in 1943 and served in every subsequent Western campaign, from Normandy to the Rhine, as the standard vehicle of American cavalry reconnaissance squadrons — the units that screened the flanks of armoured divisions and found the enemy before the tanks arrived. Free French, British and other Allied forces used it too.

8,523 were built. French M8s went on to serve in Indochina and Algeria into the 1960s, and others remained on the strength of a dozen armies for decades after that — two decades and more of service for a vehicle whose intended job had been taken away from it before the first one was delivered.

• Steven J. Zaloga, M8 Greyhound Light Armored Car 1941–91 (Osprey, New Vanguard).
• Peter Chamberlain & Chris Ellis, British and American Tanks of World War Two (Arms & Armour Press).
• R. P. Hunnicutt, Armored Car: A History of American Wheeled Combat Vehicles (Presidio Press).