Sd.Kfz. 251

There were four main model modifications (Ausführung A through D), which formed the basis for at least 22 variants.[1] The initial idea was for a vehicle that could be used to transport a single squad of 10 panzergrenadiers to the battlefield protected from enemy small arms fire, and with some protection from artillery fire. In addition, the standard mounting of at least one MG 34 or MG 42 machine gun allowed the vehicle to provide suppressive fire for the rifle squad both while they dismounted and in combat.

The armour plates were designed to provide protection against standard rifle/ machine gun bullets (like the 7.92×57mm Mauser bullet). The front-facing plates were 14.5mm thick; the sides were steeply angled, V-shape 8mm thick plates. This level of armour provided protection against normal (non-tungsten) rifle AP round, which could pierce about 8mm of vertical armour.

Positive aspects of the open top included greater situational awareness and faster egress by the infantry, as well as the ability to throw grenades and fire over the top of the fighting compartment as necessary while remaining under good horizontal cover. The downside, as with all armored personnel carriers of the era, was a major vulnerability to all types of plunging fire; this included indirect fire from mortars and field artillery, as well as small arms fire from higher elevated positions, lobbed hand grenades, Molotov cocktails, and strafing by enemy aircraft.

The first two models (Ausf. A and B) were produced in small numbers from 1939. Ausf. A and B models can be identified by the structure of the nose armor, which comprised two trapezoidal armor panels - the lower of which had an engine cooling vent. The B model, which began production in 1940, eliminated the fighting compartment's side vision slits. The C model, which started production in mid-1942, featured a simplified hexagonal-shaped forward armored plate for the engine. Models A through C had rear doors that bulged out. The C model had a large production run, but was quite complex to build, involving many angled plates. From early 1943, the D model was developed with the purpose of halving the number of angled body plates, simplifying the design and thus speeding up the production. D models can be easily recognized by their single piece sloping rear, with flat doors.

The standard personnel carrier version was equipped with a 7.92 mm MG 34 or MG 42 machine gun mounted at the front of the open compartment, above and behind the driver. A second machine gun could be mounted at the rear on an anti-aircraft mount.

Variants were produced for specialized purposes, including with anti-aircraft guns, light howitzers, anti-tank guns and mortars or even large unguided artillery rockets, as well as a version with an infrared search light used to spot potential targets for associated Panther tanks equipped with infrared detectors.

A strong design feature of the Sd.Kfz. 251 was the large track area, with the characteristic "slack track" design with no return rollers for the upper run of track. The Sd.Kfz. 251 also had the Schachtellaufwerk system of overlapping and interleaved main road wheels common to virtually all German halftracks of the period. This lowered the ground pressure and provided better traction, at the cost of much greater complexity in maintenance. The Sd.Kfz. 251 also had tank steering, whereby the normal steering wheel moved the front wheels, but after more turning of the steering wheel, the tracks are braked to cause turning, like on a tank. However, the interleaved and overlapping main road wheels shared a major problem with the Tiger I and Panther tanks that also used such roadwheel configurations - in muddy or winter weather conditions, such as those during a mud season (rasputitsa) or the winter conditions, accumulated mud and snow could freeze solid between the road wheels, immobilizing the vehicle.

The early production models of this vehicle were issued to the 1st Panzer Division in 1939 as the 'Ausf.A' or 'A-version'. There were 232 estimated Ausf.A units produced, which took place in Hannover's Hanomag, Büssing-NAG of Berlin-Oberschöneweide, Weserhütte of Bad Oeynhausen, Wumag of Görlitz, and F. Schichau shipyard of Elbing facilities.[4]

These vehicles were meant to enable Panzergrenadiere to accompany panzers and provide infantry support as required. In practice, there were never enough of them to go around, and most Panzergrenadier units had to make do with trucks for transport.[5]

In August 1943, Romania acquired a total of 27 armored half-tracks, of both the 251 and 250 types[6] followed in 1944 by 251 type and other types of armored cars to convert two cavalry divisions into armored or mechanized divisions.[7] Sd.Kfz. 251s were known as SPW mijlociu ("medium SPW") in Romanian service, while Sd.Kfz. 250s were referred to as SPW ușor ("light SPW").[8]

The Army of the Independent State of Croatia received 15 Sd.Kfz. 251 in spring 1944 and the Ustashe Militia received 12 in autumn 1944.[9]

Sd.Kfz. 251/7 "Pionierpanzerwagen"

Sd.Kfz. 251/9 "Stummel"

Sd.Kfz. 251/1 Ausf.D captured by the Polish Home Army during the Warsaw Uprising in 1944

Tatra OT-810 - a Czechoslovak post-war version of the Sd.Kfz. 251 produced by the company Podpolianske strojárne Detva in Slovakia.

There were 23 official variants, and sundry unofficial variants. Each variant is identified by a suffix to the model number; however, there was some overlap in the variant numbers.

• Sd.Kfz. 251/1 - Schützenpanzerwagen. Standard personnel carrier.
  • Sd.Kfz. 251/1 Ausf. A Ungepanzerte. Made with plain steel 5mm plates instead of armour, to make up numbers due to slow initial 251 production. Around 350 made up to mid 1940.
  • 251/1 I - with intercom facilities
  • 251/1 II - Rocket launcher (called "Stuka zu Fuß" (Walking Stuka) or Wurfrahmen 40) equipped with six side-mounted frames for launching 280 mm or 320 mm Wurfkoerper rockets.
  • Sd.Kfz. 251/1 - Falke Infrared imaging equipment for driver and MG 42 or MG 34 machine gun operator, to be used in combination with Sd.Kfz. 251/20 Uhu. Mostly Ausf. D variants.
• Sd.Kfz. 251/2 - Schützenpanzerwagen (Granatwerfer). 81 mm Mortar carrier. Carried 66 rounds for the GrW34. A base plate was also stored so that the mortar could be offloaded and used.
• Sd.Kfz. 251/3 - mittlerer Kommandopanzerwagen (Funkpanzerwagen). Communications vehicle, fitted with extra radio equipment for command use in Ausf. C and Ausf. D versions.[10]
  • 251/3 I - FuG8 and FuG5 Radios
  • 251/3 II - FuG8 and FuG5 Radios
  • 251/3 III - FuG7 and FuG1 Radios (for ground to air coordination)
  • 251/3 IV - FuG11 and FuG12 Radios (with 9 m telescopic mast); Command vehicle variant (Kommandowagen)
  • 251/3 V - FuG11 Radio
• Sd.Kfz. 251/4 - Schützenpanzerwagen für Munition und Zubehör des leIG18. Gun-towing tractor, initially for use with the 7.5 cm leichtes Infanteriegeschütz 18. Later used to tow the 50 mm Pak 38, 75 mm PaK 40 and 10.5 cm leFH 18 light field howitzer.
• Sd.Kfz. 251/5 - Schützenpanzerwagen für Pionierzug. Assault Engineer vehicle with inflatable boats stored in the side storage lockers, and light dismantleable assault bridges stored inside through loss of a seat for more storage space. Early command vehicles for Pioneer platoons (Pionierzug) were equipped with a 37 mm Pak 36 anti-tank gun mount.
• Sd.Kfz. 251/6 - mittlere Funkpanzerwagen (Kommandopanzerwagen). Command version equipped with map boards, cipher and encoding machines, and Enigma equipment. Probably only made in versions Ausf. A and Ausf. B. Replaced by the 251/3 IV command SPW.
• Sd.Kfz. 251/7 I - Pionierpanzerwagen. Another assault engineer vehicle; this had fittings to carry assault bridge ramps on the sides.
  • 251/7 II - As above but with different radio.
• Sd.Kfz. 251/8 I - Krankenpanzerwagen. Armored ambulance capable of carrying up to 8 seated casualties or 4 seated casualties and 2 stretcher cases.
  • 251/8 II - As above but fitted with FuG5 radio and 2m rod antenna. Assigned to HQ and Panzer units.
• Sd.Kfz. 251/9 - Schützenpanzerwagen (7.5 cm KwK37). Equipped with a 75 mm L/24 low velocity gun, using the same pedestal gun mount employed on the StuG III. Nicknamed "Stummel" ("stump"). In 1944, a revised modular gun mount was introduced to facilitate production that also incorporated a coaxial MG42. This universal gun mount was also used to create the Sd.Kfz. 250/8 variant and the Sd.Kfz.234/3.
• Sd.Kfz. 251/10 - Schützenpanzerwagen (3.7 cm PaK). Equipped with a 37 mm Pak 36 anti-tank gun mount. Issued to platoon leaders as a fire support vehicle. Early versions used the whole top half of a Pak 36 with full gunshield, but later ausf. C & D used a much smaller half-size gunshield so that the vehicle didn't advertise its firepower, so it looked more like a regular 251/1.
• Sd.Kfz. 251/11 - Fernsprechpanzerwagen. Telephone line layer.
• Sd.Kfz. 251/12 - Messtrupp und Gerätpanzerwagen. Survey and instrument carrier for artillery units. Never built.
• Sd.Kfz. 251/13 - Schallaufnahmepanzerwagen. Sound recording carrier for artillery units. Never built.
• Sd.Kfz. 251/14 - Schallaufnahmepanzerwagen. Sound ranging carrier for artillery units. Never built.
• Sd.Kfz. 251/15 - Lichtauswertepanzerwagen. Flash spotting carrier for artillery units. Never built.
• Sd.Kfz. 251/16 - Flammpanzerwagen. Fitted with two flame projectors and initially a rear-mounted flamethrower, detachable but still connected to the vehicle, to be operated by dismounted infantry. This was in addition to the standard forward machine gun mount. Six Sd.Kfz. 251/16 Flammpanzerwagens were authorised for issue to each Panzergrenadier regiment or in the Pioneer battalion. Though vulnerable, they were used very successfully at night to quickly attack enemy infantry who had just captured German trenches, hitting the enemy before they could consolidate and bring up the heavy weapons that would make them much costlier to defeat later. Late ausf. D versions had larger gunshields.
• Sd.Kfz. 251/17 - Schützenpanzerwagen (2 cm). Anti-aircraft vehicle armed with a 2 cm KwK38 on a pedestal mounting with a small armored turret to protect the gunner. Late war, it was issued as a platoon commander's vehicle to replace the Sd.Kfz. 251/10.
• Sd.Kfz. 251/18 I - Beobachtungspanzerwagen. Artillery observation vehicle.
  • 251/18 Ia - Differences unknown, likely different radio fit.
  • 251/18 II - Armored observation vehicle.
  • 251/18 IIa - Different radio.
• Sd.Kfz. 251/19 - Fernsprechbetriebspanzerwagen. Telephone exchange vehicle.
• Sd.Kfz. 251/20 - Schützenpanzerwagen (Infrarotscheinwerfer) Introduced in late 1944, it mounted a 60 cm infrared searchlight with a range of 1.5 km for illuminating targets at night. Known as "Uhu" (Eagle Owl), they guided IR sight-equipped Panther tanks to targets that were out of range of their own smaller infrared searchlights.
• Sd.Kfz. 251/21 - Schützenpanzerwagen (Drilling MG151s). Anti-aircraft and ground support variant equipped with a triple-mount ("Drilling" in German means "triple") of MG151 autocannon; early version being MG151/15 mm cannon, later being MG151/20 mm Luftwaffe cannon, on a Kriegsmarine triple mount. Strong firepower, especially when organised into platoons of 6 SPW. However, with a combined rate of fire of 2000 RPM, it could fire off its full load of 3000 rounds in just 90 seconds.
• Sd.Kfz. 251/22 - 7.5 cm PaK40 L/46 auf mittlerem Schützenpanzerwagen. Fitted with a 75 mm PaK 40 anti-tank gun. Probably too big a gun for the carriage, overloaded but effective, and the Yugoslav military was still using captured examples into the 1950s.
• Sd.Kfz. 251/23 - 2 cm Hängelafette 38 auf mittlerem Schützenpanzerwagen. Reconnaissance variant intended to replace the Sd.Kfz. 250/9 and fitted with the same turret mounting as the Sd.Kfz. 234/1 armoured car.[11] Probably never built.
• OT-810 - Czechoslovakian modified version known as Tatra OT-810 was made by Podpolianske strojárne Detva. About 1,500 vehicles were built during 1958–62, they have had an air-cooled diesel engine made by Tatra and armored roof over the troop compartment for better protection in case of nuclear war.[12] The vehicle was not liked by those who used it and was nicknamed "Hitler's revenge". Last vehicles were removed from Czech Army magazines in 1995.[13]
• Field modified variants - Various field modified variants also existed during World War II. There was a kit for installing an armoured map table in place of the forward MG34 mount in use in 1941. One interesting variant was made at the closing stages of the war, when German forces removed the armored bodies of damaged Sd.Kfz. 251s and installed them on light truck chassis, resulting in a wheeled variant of the Sd.Kfz. 251. At least two were made in this way judging by their number plates.

• Sd.Kfz. 7
• Sd.Kfz. 250
• Kégresse track
• M2 Half Track Car
• M3 Half-track
• Wurfrahmen 40

• Culver, Bruce; Laurier, Jim (Illustrator) (November 1998), SdKfz 251 Half-Track 1939-45, vol. New Vanguard #25 (2nd ed.), Osprey Publishing, ISBN 978-1-85532-846-4
• Doyle, Hilary Louis; Friedli, Lukas (2016). Final Developments of the Schützenpanzer Sd.Kfz.251 to Vollketten M.S.P. Kätzchen. Panzer Tracts. Vol. 15–4. Boyds, Maryland: Panzer Tracts.
• Kliment, Charles; Greer, Don (March 1981), Sd.Kfz. 251 in action, vol. Armor No.21 (1st ed.), Squadron/Signal Publications, ISBN 978-0-89747-124-4
• Ștefănescu, Alexandru V. (2020). În umbra marelui Reich: Tehnica de luptă a armatei române pe Frontul de Est (1941–1944) [In the Shadow of the Great Reich: Battle Technique of the Romanian Army on the Eastern Front (1941–1944)] (in Romanian). Târgoviște, Romania: Cetatea de Scaun. ISBN 9786065375055.

• Media related to Sonderkraftfahrzeug 251 at Wikimedia Commons
• Information about the mittlerer Schützenpanzerwagen (Sd.Kfz.251) at Panzerworld
• photos of SdKfz 251 and czech post war OT-810