The Landkreuzer P.1000 "Ratte" (translating to "Rat") was a proposed super-heavy tank design of the German Krupp concern with origins in 1942. Hitler gave this mammoth undertaking his direct blessing as the program set about to create the most powerful tank ever devised for the modern battlefield. It was an ambitious undertaking to say the least and - should it have been completed - would also have become the largest tank ever produced without doubt. Albert Speer, the German Minister of Armaments and War Production for the Third Reich, saw the fruitlessness of such an endeavor and cancelled the P.1000 in early 1943. As such, the Ratte never made it off of the drawing boards.
Externally, the P.1000 would have dwarfed any other tank in production at that time by a long mile. The immense size would have been something to behold with as many as eleven large road wheels affixed to either track side. The tracks themselves would have measured nearly four feet in width. The hull would have been largely conventional in design and construction by 1942 standards with flat skirted side armor and an angled front and rear hull armor facings. Armor at certain points would have reached between 150mm and 360mm in thickness. The turret would have also sported ballistics deflecting armor for maximum protection. Dimensions were pretty impressive with the P.1000 sporting a height of 11 meters, a width of 14 meters and a length of 35 meters. The overall operational weight was expected to reach 1,000 tons (2,000,000 lb).
In essence, the P.1000 was to have been a large rolling battle platform armed to the teeth. The massive turret would have been positioned well-forward on the hull with primary armament envisioned as 2 x 280mm 54.5 SK C/34 guns fitted in side-by-side mounts, these based on powerful naval warship guns - necessitating the need for a custom-designed to house the twin-artillery arrangement. Essentially, the turret would be a modified heavy cruiser gun emplacement (possibly from the Gneisenau-class) with full 360-degree traverse - albeit slow to move such a heavy fixture. As such, firing "on-the-move" would not have been possible. Secondary armament became a 128mm KwK 44 L/55 anti-tank gun as well as 8 x 20mm Flak 38 anti-tank cannon systems, the latter to combat incoming, low-flying enemy aircraft as the p.1000 would have made a tempting, slow-moving target for many-and-airmen. The 128mm gun system would have been either mounted in the main turret with the twin naval guns or seated in an individual (albeit smaller) turret fitted to the rear of the hull (the exact location of this armament was never formalized). A further fitting of 2 x 15mm MG 151/15 autocannons would have also been part of the armaments package for the P.1000 making for one impressive battlefield combat system. A minimum estimated crew of 20 personnel (though as many as 40) would have been required to man the various onboard systems - a throwback to the large, boxy German tank design of World War 1, the A7V Sturmpanzer-Kraftwagen, which used 18 crew and fielded a 57mm main gun and up to 5 x 7.9mm machine guns.
To propel such a behemoth across the battlefields of Europe, Krupp suggested the use of either 8 x Daimler-Benz MB501 20-cylinder marine diesel engines developing an estimated 16,000 horsepower or 4 x MAN V127Z32/44 24-cylinder marine diesel engines of 17,000 horsepower output. The former engine type was utilized in existing German E-Boat systems while the latter was prominent in U-Boat submarine designs. Though an optimistic top speed of 25 miles per hour was envisioned, this was suspect with all things considered. Durable operational range was also of concern, though a hefty 120 miles was entertained. It is assumed that the P.1000 would have been extremely limited in most facets of its general operation - speed, range and reliability - leading many to doubt its true effectiveness in live fire use.
As it stood, the Landkreuzer P.1000 proved just another tangent for Adolf Hitler to commit valuable wartime resources and engineering manpower to. On paper, the P.1000 was a true threat with enough firepower and inherent armor protection to both destroy anything on the modern battlefield and survive most anything thrown in its direction. In reality, the system would have not added much in the way of changing the downward-spiraling German fortunes by the late-war months. The sheer size of the P.1000 would have extremely limited its tactical use and battlefield effectiveness and off-road travel would have proved impossible, more than likely limiting the tank system to operations as a static, fixed defensive weapon protecting a portion of territory within range of its guns. Weight alone would have forced many-a-European-road to simply crumble under the mass of its wheels. Additionally, no bridge in Europe would have supported the passing of the P.1000 requiring transport by railway cars constantly under attack from Allied fighters - however, even railway transport was not really a viable transport form for such a large and heavy vehicle - her width alone would have precluded such use. Furthermore the use of multiple engines in a joined complex arrangement within one hull would have proven a maintenance nightmare for accompanying crew not to mention headaches for when in search of useful spares. With that said, if used at all in combat, the P.1000's reach would have been severely limited by these inherent design restrictions.
While the P.1000 project eventually foundered, the Panzerkampfwagen VIII Maus ("Mouse") went on to become the largest tank to be built in World War 2, though only reaching prototype form in two examples before the end of the war. The P.1000 would, therefore, fall to the pages of history.