The United States of America declared war on Germany on April 6th, 1917 which, on many levels, spelled the end of whatever advantages the Germans held. The fresh manpower would relieve beleaguered British, French and Belgian forces and provide a much-needed "shot in the arm" for the war effort. In June of 1917, the U.S. government held talks with the British about procuring the latest available British tanks for service in the United States Marine Corps (this by way of the United States Navy). The focus initially settled on the Mk VI tank then in development, this to become the primary British tank of the war and a further evolution of the original Mk I line ("Big Willie"). At the same time, Britain was in need of manufacturing assistance and were secretly looking to America to help to fulfill the demand now that the Americans had officially entered the conflict. Though the Mk VI might have been a serviceable system in its own right, the Americans believed that they could apply their own expertise in the design of an improved and more powerful tank form to fall in line with American industrial capabilities of the time.
Before the U.S. Navy could move to send its people to Britain to begin work on the new tank (to be known as the "International" tank, noting the multi-nation involvement), the American Department of War relocated the need for a new tank to the U.S. Army. American Major H. W. Alden joined his British counterparts in London on October 3rd, 1917, and the new tank design was penciled out. Winston Churchill, then the Minister of Munitions, signed off on the design after a December 4th, 1917 meeting. The lofty production total consisting of 1,500 examples was to be met by the end of 1918 (many still assuming the war would progress into 1919). The U.S. would be responsible for the major internal components including the transmission, engine and rear sprockets whilst the British would contribute to the armor plating, structural supports, weapons as well as applicable ammunition stocks. France would become the third major player in the agreement and take on orders of the tank as well as eventually provide French-based factories for local production closer to the Front. In the end, the Allies would have, in their stable, a standardized tank system that could promote commonality of parts across the different armies of the West with support through like-minded manufacturing practices should the war continue beyond 1918. So as to not endanger the future of the Mk VIII effort, all British work on the aforementioned Mk VI tank was stopped in December of 1917.
In some ways, the new Mark VIII bridged the design gap between those early lozenge-shaped tanks of the war and those shapes to come during the inter-war years. It sported a compartmentalized interior that separated the crew from the engine. The large powerplant (either a V-12 Liberty or V-12 Ricardo gasoline engine of 300 horsepower) was fitted to the rear of the hull and cut-off from the crew compartment by a bulkhead. The bulkhead served to deflate the deadly fumes and high-decibel noise coming from the engine. The engine was tied to an epicyclic gearbox allowing for two forward and two reverse speeds. The external side profile of the tank showcased a tear-drop appearance as well as long-running tracks extending past the length of the hull on either side and at either hull end. The track design served well in allowing the Mark VIII to traverse the network of trenches and craters littering the World War 1 battlefields. The suspension system was unsprung which promoted a very rough ride but simplified production. The hull was adorned with a slab-sided superstructure that allowed the tank commander a view of the action through four vision ports fitted to a cupola. The commander stood over a platform housing the supply of 57mm projectiles for the main guns. The crew was led by the tank commander with the driver situated in the forward hull and an onboard mechanic seated near the engine to the rear. A gunner and a loader manned each cannon position while machine-gunners handled the available defensive machine guns to prevent infantry attacks against the tank. A special deflection plate was affixed to the rear upper hull to assist the rear gunners in engaging enemy infantry to the vehicle's lower "six" - a defensive weak spot in any tank design. Such a detail allowed gunners to engage enemy infantry down in the trenches as the tank passed over. Armor protection was 16mm at its thickest while operational range was limited to 50 miles with a top speed of 6.5 miles per hour.
Armament centered around 2 x British 6-pounder (57mm) OQF guns mounted in the side sponsons (sponsons being structural outcroppings common to many early tanks, this before the turret became standardized throughout tank designs). These were given limited traverse but could attack enemy targets forward, to the sides and under the sides of the tank (a hull-roof-mounted turret would not have been able to contribute to the latter). The sponsons were also made to collapse inward so as to decrease the width of the tank when transported by rail. Self-defense was a bevy of British- or American-made .30 caliber machine guns as needed.
Despite the expected 1,500-strong order required by years' end, production never fully got underway. Factories built on French soil never got up to speed and other pursued avenues - both in the U.S. and in Britain - never materialized to the point that a single tank could be outputted. The first American prototype was not even completed until September 28th, 1918. By the time the weapons were added, the war had concluded and the quantitative wartime orders were scrapped. The British prototype was made ready on the day of the Armistice itself - November 11th, 1918.
Despite their own 1,500-strong order, only 5 British Mk VIII tanks were delivered for army service and these were relegated to training only. Construction was completed on some 24 more examples (made possible by way of available spare parts) though all remaining British Mk VIIIs were ultimately scrapped.
The Americans fared a better with their Mk VIII production for at least 100 unitswere produced between 1919 and 1920, ultimately supplying the 67th Infantry (Tank) Regiment. These tanks survived up to about 1932 to which they then ended up in Army storage facilities. At the outbreak of World War 2 during September 1939, the Canadians were in dire need of tanks for training crews and purchased the remaining American Mk VIIIs on the cheap. Such ended the legacy of the Mark VIII "International Tank".
The U.S. 301st Tank Battalion (Heavy) - later becoming the 17th Tank Battalion (Heavy) - made use of the tank. From 1921 to 1922, Major Dwight D. Eisenhower - the future general of World War 2 fame - was put in charge of the unit as commander. Only a few Mk VIIIs exist today as exhibit pieces on both U.S. and British soil. One example is on display at the Aberdeen Proving Ground in Aberdeen, Maryland.
The Mark VIII* (Star) was a proposed lengthened version of the Mark VIII, intended to provide better trench crossing support. The project came to naught never went past the design stage.
The "Steel Beast" appearing in the motion picture "Indiana Jones and the Last Crusade" was actually based on the design of the Mark VIII with the most notable exception in the movie being the addition of a traversable turret set atop the armored superstructure.
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