Warbands...they can be a very powerful part of your overall offensive game plan, or they can totally disrupt a carefully thought out plan of battle. Warbands historically were of value because of their numbers and the ferocity they exhibited, at least initially. Often they were from the same tribe, village or region, thus they knew each other and often had relatives as well as friends alongside while on 'campaign.'

Controlling warbands takes patience and a good command control. Once they come to within their normal movement range of any eligible enemy target, they will charge them. They are considered to be fanatics up to and including the first round of a close combat, so they will go charging into delaying terrain even though they have little or no chance of catching an elusive foe.

There is really only one sure way to restrain warbands. You are forced to use one of your valuable orders to give a warband a Recover order if you wish to keep it from charging. It may then only sit there and do nothing else but fire missiles, if eligible to shoot...they are not prevented from doing that! If they do shoot, immediately remove the Recover order.

Another way is to try to avoid having them get within their normal movement range of an eligible enemy target. This can be tricky as a wily opponent will rush skirmishers up to tempt the warbands to precipitously charge them. Keeping warbands in woods can work. They really can't see anything until the enemy is within 1' (2"), so this prevents them running off and charging immediately, but if you put them in forests, they may never find their way out....

Placing them behind hills can work, but placing them behind other friendly units will not. Fanatics will charge anything they can see, and they can see through other units. Seeing these guys go charging through your own units is not a pleasant way to start a battle.

Once the warbands fight their initial round of a close combat, they are lowly warriors, no longer receiving the fanatic morale bonus, but also no longer automatically attacking either.

I've used armies of warbands and they do require careful command. When they are commanded well, they can be deadly. When they get out of hand, however, it makes for a long afternoon or evening....