The First World War was the armed conflict in which for the first time numerous types of weapons were used, which are considered absolutely familiar today. Tanks are a prime example of an innovative arsenal. One glance at the old photos is enough to be surprised at how the early models are strikingly different from the combat vehicles currently in use. In particular, the presence of a mysterious "tail" is striking.
As you know, the history of tank building began with heavy vehicles. The first models of the famous British "rhombuses" had a steering wheel in the tail.
Light tanks began to be used only in the final battles of the First World War. In the interwar years, a lot of attention was paid to light tanks. The development of new models was carried out primarily on the basis of the existing experience of their use in the First World War.
Overcoming trenches was an important problem for tanks in World War II. It often happened that tanks got stuck even in relatively small holes. There are known cases when tanks that ended up in a trench overturned or simply skidded and could not go further, thus becoming absolutely useless in battle. At the same time, the situation was the worst with light tanks.
When overcoming the trench, there was a high probability that the light tank would simply tip over onto its back. Also, when overcoming irregularities, the heavy stern often hit the ground hard, which led to damage to important components. To avoid all this, the engineers came up with the idea of installing such a "tail" on the stern of light tanks. On the one hand, it did not allow the tank to tip over when leaving the trench. On the other hand, it made the exit into the pit smoother and did not let the engine hit the ground.
However, already in the 1930s tank building all over the world made a new big step forward, and the need for "tails" for light tanks completely disappeared.
Continuing the topic, read about why the giant Mk VIII did not take part in the world wars, despite the fact that he had every chance.