Nel 1932 la Germania aveva contratti con vari produttori per realizzare prototipi di veicoli semicingolati che avrebbero coperto diversi ruoli. Nel 1935 fu riconosciuto che un veicolo versatile, capace di trasportare una squadra di dieci uomini, avrebbe permesso alla fanteria di tenere il passo dei veloci panzer. I veicoli da trasporto truppe, designati Gepanzerter Mannschraftstransportwagen (Gp MTW) allo stato di prototipi, furono lanciati in produzione nel 1938. Il telaio era prodotto dalla Hanomag, la carrozzeria dalla Büssing-Nag, ed il veicolo fu ufficialmente ridisegnato come SdKfz 251, o come Mittlerer Schützenpanzerwagen (veicolo medio corazzato per fanteria). I primi veicoli di questo tipo prodotti presero parte all’invasione della Polonia nel 1939. Inizialmente gli esemplari prodotti furono pochi (348 nel 1940), ma nel 1942 raggiunsero il picco di 7800,

per un totale, fino al 1944, di 16000. Il vantaggio del SdKfz 251 era la capacità di poterlo adattare ad ogni ruolo, tanto che ne furono costruite 22 varianti. Il 251/1 era la variante base da trasporto truppe, il 251/2 aveva un mortaio da 80 mm, mentre il 251/3 era equipaggiato con una radio; il 251/4 era usato per il traino di artiglierie, il 251/5 trasportava squadre di genieri insieme ai loro canotti gonfiabili ed il 251/6, o anche Kommandopanzerwagen, era riadattato a posto di comando con tavola per mappe, calcolatore e macchine codificatrici. Il 251/7, anche detto Pionierpanzerwagen, era una variante del 251/5 e trasportava rampe d’assalto, canotti e materiale per demolizioni; il 251/8, o Krankenpanzerwagen, era convertito in ambulanza corazzata, ma le prime varianti ad ospitare cannoni furono la 251/9 e 10 (Stummel) rispettivamente con un 75 mm KwK L/24 e un 37 mm PaK 36. Il 251/11 era usato per stendere cavi telefonici e i 251/12 – 15 servivano da osservatori di appoggio a postazioni di artiglieria. Probabilmente la versione più temibile fu la 251/16, o Flammpanzerwagen, che aveva due bocche da 14 mm capaci di sparare 80 fiammate da due secondi l’una, grazie a due serbatoi gemelli da 700 litri.  I 251/17 – 18 avevano cannoni antiaerei e furono migliorati con la versione 251/21; il 251/19 era un’altra versione di supporto alle artiglierie e comunicazioni mobili mentre la 251/20, o Uhu, fu equipaggiata con luci di ricerca all’infrarosso ed usata come supporto ai Panthers nel combattimento notturno. La versione finale fu la 251/22, equipaggiata con cannone da 75 mm PaK 40, come una veicolo anticarro “di riserva”.

  In 1932 contracts were placed with a variety of German manufacturers to produce prototypes for half-tracked vehicles which would fulfil a number of roles. By 1935, it was recognised that a versatile vehicle capable of carrying a squad of ten men would allow infantry to keep pace with the fast-moving panzers. The armoured troop carrier, designated Gepanzerter Mannschrafts-transportwagen (Gp MTW) at prototype stage, was rushed into production in 1938. The chassis was built by Hanomag and the body by Büssing-Nag, and the vehicle was officially redesignated the SdKfz 251, or the Mittlerer Schutzenpanzerwagen (medium infantry armoured vehicle). The first production vehicles took part in the invasion of Poland in 1939. Initially, production figures were low (348 in 1940), but by 1944 had reached a peak of 7,800, and by 1944 around 16,000 had been built. The beauty of the SdKfz 251 was its ability to suit any purpose. There were 22 variants. The 251/1 was the basic infantry carrier, and the 251/2 was fitted with an 80 mm mortar, whilst the 251/3 was equipped with a radio. The 251/4 was adapted for use as a gun tractor (105 mm gun or anti-tank), the 251/5 was designed to carry assault engineers along with their inflatable boats and assault bridges, and the 251/6 or the Kommandopanzerwagen, was refitted for commanding officers with a map board and cipher and encoding machines. The 251/7, or the Pionierpanzerwagen was a variant of the 251/5 and carried assault ramps, boats and demolition equipment. The 251/8, or the Krankenpanzerwagen, was fitted out as an armoured ambulance, but the 251/9 and 10 (Stummel) were the first to house guns - the 75 mm KwK 37 L/24 and the 37 mm PaK 36 respectively. The 251/11 was equipped to lay telephone cables and the 251/12-15 were specialist artillery vehicles used by assault gun and artillery units as spotters, surveyors and ranging vehicles. Perhaps one of the most potent variants was the 251/16, or Flammpanzerwagen, which had two 14 mm projectors capable of hosing 80 two-second bursts of flame from their twin 700 litre (154 gallon) fuel tanks. The 251/17-18 were fitted with flak guns and used as anti-aircraft vehicles by Panzer Grenadier and Panzer units; the 251/21 was an uprated 1944 version. Whilst the 251/18 and the 251/19 were used for artillery observation and as a mobile telephone exchange, the 251/20, or Uhu, was fitted with infra-red searchlights and used with Panthers for night fighting. The final version, the 251/22, was fitted with a PaK 40 75 mm gun as a last-ditch anti-tank vehicle.