One of Germany's favorite weapons from World War I that was subsequently brought into World War II as well was giant, railroad carriage-mounted artillery pieces. Thus, Krupp was contracted to develop several new railway guns to support Hitler's Blitzkrieg, which emerged as the K5 series. Mounted in a long armored carriage, the K5 could fire a 550 pound shell at distances reportedly up to 38 miles. K5s first saw action during the invasion of France in 1940, and would go on to serve as defensive units during the Allied push into France and Italy towards the end of the war.

The two most famous K5s were the "Robert" and the "Leopold" of the 280mm K5(E) model. Both were used to shell American troops on the Anzio beachhead in Italy, the heaviest weapons employed against the Allied forces during the invasion of Italy. Despite the massive size of the gun, Allied bombers and naval batteries were never able to destroy the guns, and reconaissance planes could never find them. The probable positions were heavily bombarded countless times, but the guns kept firing. This aura of mstery and seeming invincibility soon earned both guns the nickname "Anzio Annie" (apparently, the troops thought that only one gun was firing at them, rather than two). In reality, "Anzio Annie," when not firing, was withdrawn into mountain tunnels along the railroad, protecting them from prying eyes and Allied counter-fire. When the Allies broke out of the beachhead, the Germans were forced to abandon their rail-mounted weapons of mass destruction and attempted to destroy them, badly damaging both guns. Several days later Allied troops recovered both guns, and were able to salvage the "Leopold" using parts from the "Robert," and the rebuilt gun was shipped to Aberdeen Proving Grounds for tests, where it remains to this day - the sole surviving German WWII railway gun.

K5(E) 280mm "Leopold" aka "Anzio Annie" Railway Gun Stats:
Type: Railroad artillery
Manufacturer: Krupp
First deployed: 1940

Crew: 15 to 25
Length: 30 m
Width: 2.69 m
Overall Weight: 214 tons

Gun caliber: 280mm
Gunbarrel length: 21.6 m
Warhead type: HE
Muzzle velocity: 1120 meters per second
Rate of fire: 1 round per 3-5 minutes
Range: 61km

Elevation: 55 degrees
Traverse: 5 degrees

Operators: Germany