The 15-cm schwere Feldhaubitze 18 (sFH 18) became the standard 149mm howitzer for German Army divisions of World War 2 (1939-1945). The weapon was originally developed to be horse-drawn (as all German artillery at the time was) but was later modified to be towed by mechanized means. A compromise was met to fit the Rheinmetall gun atop the Krupp carriage after several strong submissions were submitted for trials by both parties.
After the German invasion of the Soviet Union and the Soviet response thereafter, sFH 18 systems were found to be out-ranged by their counterparts so this forced modifications to be made to help increase engagement ranges. However, changes had an ill-effect on the barrels and recoil mechanism through excessive wear. As such, the modification program was abandoned though the remaining sFH 18 guns were still operated until their battlefield usefulness had expired. Modified guns went under the designation of "15-cm sFH 18(m)".
The sFH gun family came to be mounted on a motorized chassis and these vehicles were known as "Hummel" - or "Bumblebee" - and became a respected Self-Propelled Artillery (SPA) system by the end of the war in 1945. sFH 18's were also present along Hitler's famous "Atlantic Wall" - the long-running line of fortifications and guns set along the French coast between France and Britain in attempt to thwart any Allied invasion from the North/West.
Several world powers continued fielding the sFH 18 after the war in large numbers including Czechoslovakia, Portugal and many South American and Central American countries. such was the design excellence of the gun.