The Hummel was a hastily designed and produced self-propelled howitzer that carried one of the best German medium/heavy field guns of WWII, the 15cm Schwere Feldhaubitze 18 (sFH 18). Alkett in Borsigwalde originally designed the chassis, known as the "Geschutzwagen III/IV", as a makeshift solution to the problem of providing a large tracked gun platform. For this purpose, portions of the well-proven chassis components of both the Panzer III and Panzer IV tanks were utilized. Mild steel prototypes of both the Hummel and her sister, the Hornisse/Nashorn (mounting the 8.8cm Pak 43/1 L/71 gun) were exhibited to the German general staff in October 1942, and with their approval series production began on both vehicles in early 1943. The mounting of the gun on the Geschutzwagen III/IV was done at the Deutsche Eisenwerke in Duisburg.
By the end of the war, there had been as many as 724 Hummels built (ten by rebuilding) and perhaps as many as 157 ammunition carrier versions without the big gun, called "Munitionstrager". Although Hummel (Bumble bee) was the name originally given to this SPH, it was abandoned upon Hitler's orders in February of 1944 because it did not sound powerful enough for him. German reports indicate that Hummels arrived on the battlefield by May 1943.
Typical crew number is reported to be six and included a driver, gun captain/radio operator, two gun layers (K1 and K2) and two loaders (K3 and K4), although it varied depending on conditions. The vehicle and crew were only part of a much larger working group, a heavy battery being comprised of four Hummels and two munitions carriers would include around 58 soldiers and officers.
By all accounts the Bumblebee was a very successful piece of support artillery, providing just the kind of mobile fire support required by the new style of blitzkrieg fighting perfected by the Germans in the early years of the war. Unfortunately for them, by the time the Hummel went into production and was finally delivered to the troops, most of this type of fighting was a thing of the past and the Germans were to begin a mostly defensive withdrawal from their earlier front lines. Even in this role the Hummel was important as a vehicle that could deliver devastating and concentrated fire on a target and then move to a new location quickly to defend itself from counter battery fire.