The history of KV-6 is they are separated from 3 Tank brothers. Especially on the first episode of them, they were at a bridge, the brothers try to blow up the bridge so the German tanks can't capture it. Their mission was a success but it was near suicide as they almost died in the battle. Stalin calls the crane tank to rescue them, one of them drowned and the 2 others are unconscious. The crane tank said it was difficult to repair them, so he combined them into KV-6. Stalin liked the warrior 