World War One Tanks
Tanks were only just invented in World War One, and there weren't that many countries that had made a tank.
In fact, the Germans only made one type of tank throughout the entire war because, at the time, they couldn't see the point of them. And they only built that tank because the British had introduced them first.
The name "tank" comes from the British. When the first tanks were being built, they were disguised as water tanks to maintain secrecy.
During the first tank battles, the power of tanks often came not from their armor or weapons, but from the fact that they induced terror in infantrymen who had never seen anything like them before. The appearance of a tank could cause enemy infantrymen to flee long before they were within the tank's firing range.
Regardless of their flaws, the tanks of WWI are interesting because they were all experimental in nature, no one had really hit on that perfect design for a tank, and they all had the little quirks you get when something is created for the first time - be it steam train, airplane or tank.
(Weights are in long tons and kilograms.)