The 12 part series on the tanks predecessors began with chariots, however not all of the ancestors are vehicles.
The armoured knight, with his lance, mounted on a heavy horse, was the embodiment of the tank on the medieval battlefield. Strong, hard hitting and very difficult to bring down.
Armoured horsemen, clad in chain mail, accompanied the Norman Army at the Battle of Hastings but over the next five hundred years armour developed until it completely covered the man. This was the age of chivalry although, if you read Malory’s Morte d’Athur chivalry was very selective. Killing fellow knights, for example, seems to have been perfectly acceptable.
We are told that to begin with mounted knights felt so secure that they fought in a body without any help from lesser beings and that they only accepted the hoi pilloi in the field in order to have something to kill. But the foot soldiers got their revenge in the end with the powerful Welsh longbow and, later, the firearm. Thus by the time of the English Civil War the cumbersome armoured knight was on the way out.