M3 Half-track

Armoured warfare creates a problem the tank cannot solve: infantry has to arrive at the same time as the armour, and infantry on foot cannot keep up. Germany answered with the Sd.Kfz. 251; the United States answered with the M3, a simple half-tracked box developed from an existing scout car, with wheels at the front for steering and tracks at the back for grip.

The comparison between the two is the whole story of Allied production. The German half-track was the better vehicle — better protected, better shaped, purpose-designed — and around 15,000 were built. The American one was cruder, and about 53,000 were built. That ratio decided which armies were fully mechanised and which were not.

The M3 is the reason American armoured divisions worked the way they did. An armoured division that can only move at the speed of its tanks is a division whose infantry arrives late, exhausted, and after the moment has passed — and in 1940 almost every army still moved its infantry on foot or in unarmoured lorries that could not follow tanks off a road.

The alternatives tell the story. The British largely relied on lorried infantry and had comparatively few armoured carriers; the Red Army, which built almost none of its own, resorted to tank desant — infantry riding on top of the tanks, gripping the engine deck, completely exposed to fire and to the tank’s own gun blast. Against that, a thin open box with a floor and sides was a considerable advance: 6–13 mm of plate, room for thirteen men including the crew, and ~72 km/h on roads — enough to hold station with the tanks it followed.

Its crews were under no illusions. The M3 carried 6 to 13 mm of armour and was open on top, which meant it stopped rifle fire and shell splinters from the side and nothing at all from above — and an air-burst shell over a loaded half-track was catastrophic. The nickname followed: the Purple Heart Box, after the medal awarded for being wounded.

The judgement was harsh and not entirely fair. The vehicle was never meant to fight; it was meant to carry thirteen men to where the fighting was, quickly, with enough protection to survive the journey. Used as intended it did that job better than walking, which was the alternative, and units that treated it as a battle taxi rather than a fighting vehicle lost far fewer men in it.

The M3’s real contribution was its adaptability. The same hull carried mortars (M21), 75 mm guns (M3 GMC, which fought in the Philippines and North Africa), 105 mm howitzers, anti-tank guns, radios, ambulances, engineer stores and rocket launchers.

The most feared version had no anti-tank role at all. The M16 Multiple Gun Motor Carriage mounted four .50 calibre machine guns in a powered turret for anti-aircraft work, and when the Luftwaffe stopped appearing it was turned horizontally: against infantry in the open it was so destructive that troops on both sides called it the meat chopper. The M16 was one of four principal variants on the same chassis, alongside the M21 mortar carrier, the M3 GMC with its 75 mm gun and the Lend-Lease M5.

The M3 went everywhere and to everyone. It served the US Army and Marine Corps on every front, and went in quantity to the British Commonwealth and the Soviet Union under Lend-Lease — the Red Army, which built almost no armoured personnel carriers of its own, received thousands and used them hard.

To keep the supply flowing, International Harvester built a near-identical vehicle, the M5, specifically for Lend-Lease, freeing the original production for American units. By 1944 the same silhouette could be found in Normandy, in Italy, on the Eastern Front and in the Pacific, in a dozen different armies, doing a dozen different jobs.

The M3 outlived its war by decades, and nowhere more visibly than in Israel. The IDF took M3s wherever it could find them from 1948 onwards, rebuilt them repeatedly with new engines and weapons, and kept them in front-line service through the wars of 1956, 1967 and 1973 — with some still in secondary use into the 1980s.

Other armies did the same on a smaller scale across Latin America, Asia and Europe. The production figure is what made it possible: with roughly 53,000 built in four years, spares and complete replacement vehicles stayed available for decades after 1945, and the running gear was plain enough for a lorry workshop to maintain.

Judged as a fighting vehicle the M3 is easy to criticise, and its own crews did. It was thin, open, and offered a false sense of security to men who would have been safer on foot in some situations. The German equivalent was better in every respect that can be measured on a vehicle.

Judged as a logistical and organisational achievement it is one of the most consequential vehicles of the war. Roughly 53,000 of them meant that American infantry could move at the speed of American tanks, that Soviet infantry could ride, that artillery and mortars and anti-aircraft guns could follow an advance without stopping to unlimber. The Sd.Kfz. 251 was the better half-track; the M3 was the one that mechanised the Allied armies.

• Steven J. Zaloga, M3 Infantry Half-Track 1940–73 (Osprey, New Vanguard).
• Peter Chamberlain & Chris Ellis, British and American Tanks of World War Two (Arms & Armour Press).