The general appears to be a truck that gives nearby soldiers a red effect and is made in the fort. It was added in the most recent update. The general has no attack but gives foot soldiers around him a damage buff increase.
Mainly in the middle of a game, a general can be used to buff soldiers who attack by going near them. They are generally used for that purpose in big armies.
The buff from a general does not stack.
While a general may buff soldiers, it does not attack anything and can be destroyed fast by another army. To keep your general protected, it should be kept in the middle of an army with or without tanks surrounding it.