Soviet Union World War Two Tanks
The Soviet Union was slow to develop the tank during the period prior to WWII. In fact, they borrowed and bought tanks from the British for use during the Russian revolution.
However, by the end of World War Two the Soviet Union had some of the best tanks available at the time.
The Russian T-34 tank, after a slow start in early development, became the mainstay of the Soviet army and continued to be used well after WWII by Russia and many other countries around the world.
The T-34 was a masterpiece of technology and simplicity of design. It was superior to its German counterparts and could be built in half the time.
When the Germans first encountered it, they were shocked to find that the Russians, who previously had not been able to produce very good tanks of their own, now had a tank that was practically undefeatable.
(Weights are in long tons and kilograms.)