The Russian Czar TankWorld War I was known as the war which introduced the tank to warfare.  However

The Russian Czar TankWorld War I was known as the war which introduced the tank to warfare.  However tanks were new technology, and the first designs were extremely odd compared to later designs.  The Russian Czar tank is certainly no exception.  Designed around 1914 and 1915, the Czar tank didn’t have caterpillar treads like most other tank designs.  Instead it was more like a gigantic tricycle with two 9 meter diameter wheels at the front and a single 1.5 diameter wheel at the rear.  Each of the large wheels had its own 250 horsepower engine.  Overall, this large monstrosity stood at 8 meters high and was 12 meters wide.  The Czar tank was to be armed with 3 large guns, one six pounder on a 360 degree traversing turret at the top of the tank, and two 9 pounders located at ports on the side.  A number of 7.62mm machine guns were also to be mounted around the tank.The Czar tank was tested in August of 1915, when its many design flaws became readily apparent.  First and foremost, the small wheel at the rear was very prone to getting stuck in mud, soft ground, trenches and ditches.  Secondly, that Czar tank made an excellent target for artillery due to its large size and slow speed.  Only one prototype was ever built, which was taken apart for scrap in 1923. -- source link

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