United States, 1942–1945 — Type: Light Self-Propelled Howitzer
Chassis: M5 and M5A1 Light Tank
Main Armament: 75mm M2 or M3 Howitzer
Armor: 13–38 mm (welded hull)
Origins and Development
The M8 HMC began as the T47 project in early 1942, intended to replace half-track-based artillery like the T30. The prototype was based on the Cadillac M5 Light Tank and featured a redesigned upper hull with a new turret and front-mounted driver positions. Standardized as the M8 HMC in May 1942, production ran from September 1942 to January 1944, with a total of 1,778 vehicles built by Cadillac (Franz, 2008, p. 2):contentReference[oaicite:0]{index=0}.
Earlier prototypes included the 75mm HMC T1, T3, T18, and T47. The M8 replaced the 75mm HMC T30 (500 units built), which had limited protection and mobility (p. 2):contentReference[oaicite:1]{index=1}.
Production and Variants
- Chassis: Early production used the M5 hull; later units used the M5A1 chassis
- Late production features: Sand shields, solid-spoke wheels, stowage box on rear plate (p. 2):contentReference[oaicite:2]{index=2}
- Towed Equipment: Last 178 vehicles had pintle mounts for M8 armored trailer or M10 ammunition trailer (p. 3):contentReference[oaicite:3]{index=3}
No significant variants were developed; one prototype was tested with the M3 75mm gun from the M4 Sherman for tank destroyer use, but the concept was dropped in favor of the T70/M18 Hellcat (p. 7):contentReference[oaicite:4]{index=4}.
Operational Use
The M8 HMC was deployed primarily as organic indirect fire support in mechanized cavalry reconnaissance squadrons. It saw action in Italy, northwest Europe, and the Pacific Theater (p. 2):contentReference[oaicite:5]{index=5}.
- 174 M8s were delivered to the Free French Forces via Lend-Lease and saw combat from Normandy through to the liberation of Paris (pp. 2, 13–15):contentReference[oaicite:6]{index=6}
- M8s were frequently seen towing M10 trailers or with M8 armored trailers for extended support operations (p. 15):contentReference[oaicite:7]{index=7}
Technical Evaluation
The M8 was widely praised for:
- Mobility and reliability, thanks to twin Cadillac engines
- 360° turret traverse and full crew protection
- Dual-purpose use: indirect fire support and close infantry coordination
However, it had limitations:
- Thin armor (max 38 mm front)
- Limited HE payload (46 rounds) and crew cramped in combat (Franz, 2008, pp. 3–4):contentReference[oaicite:8]{index=8}
- No overhead cover made it vulnerable to shrapnel and snipers
Technical Summary
| Feature | Specification |
|---|---|
| Crew | 4 |
| Weight | 15,555 kg (combat) |
| Armor | 13–38 mm |
| Main Armament | 75mm Howitzer M2 or M3 |
| Secondary Armament | .50 cal M2HB + 1× .45 SMG, 3× .30 carbines |
| Engine | 2× Cadillac V8 (2× 110/148 hp) |
| Speed (road) | 56 km/h (35 mph) |
| Range (road) | 275 km (172 mi) |
| Transmission | Hydra-Matic (6 fwd, 1 rev incl. transfer) |
| Suspension | Vertical volute spring (VVSS) |
| Fuel Capacity | 326 liters |
| Radios | SCR-510 |
| Trench Crossing | 1.65 m |
| Fording Depth | 92 cm |
| Traverse | 360° |
| Elevation | -20° to +40° |
| Ammunition | 46× 75mm, 400× .50 cal, 600× .45 cal, 8 grenades |
Source
Franz, Michael. 75mm Howitzer Motor Carriage M8. Tankograd Technical Manual Series No. 6014. Erlangen: Tankograd Publishing, 2008.