Before going to war with Europe to begin World War 2 (1939-1944), the German military understood the need for reliable, effective artillery pieces and appropriately invested much time, material, and financing to developing strong ranged weapons. This was further driven home when it was understood that the German advance would be slowed by the many forts dotting the European countryside and thusly large-caliber siege howitzers were investigated. From the period of 1935 to 1938, Rheinmetall fleshed out a new 238mm caliber weapon firing a 334lb High-Explosive (HE) shell. After completing its requisite trials, the gun was ordered into service as the 24cm Kanone 3 (K3) and production began in 1938 under the Krupp brand label.
The K3 gun system utilized multiple operating crew for total efficiency. The massive shells were loaded at the breech through a horizontal sliding block arrangement. The box trail carriage was a four-wheeled towable assembly holding both the gun mounting hardware and aiming controls as well as the gun tube itself. Inherent traversal was 6-degrees from centerline though, when fixed into play and made readied to fire on its platform by having the roadwheels raised, the gun was given a complete 360-degree traversal. The recoil mechanism was the same as first used on the 21cm Morser 18 series guns - a dual-recoil system in which the gun tube recoiled in its cradle as normal while the carriage followed along its own recoil mechanism. This feature provided a very accurate gunnery platform for the crew with ranges reaching out to 23 miles with a muzzle velocity of 3,182 feet per second. Rate-of-fire was one round-per-minute.
To facilitate transport of the system (beyond its towable nature), the K3 was designed to break down into six major components. One of these was an electric generator that also facilitated setup of the weapon by way of electrically-powered winches. This allowed the design to do away with a more complex and cumbersome crane approach seen in other large guns of this class.
In practice, the guns offered relatively good service but the Army required more from such a large and expensive artillery piece, particularly one with such a high operator commitment. Only four were available in time for the German invasion of Poland in September of 1939 and the situation was not bettered in time for the Battle of France the following year. Only about fourteen guns were ever made and attempts to bring more out of the system fell to naught before the end. Production ended in 1944 and the system saw its final combat action in 1945, the final year of the war.