Why can't units properly encircle enemies?

[Omisan]

Whenever you have a large melee unit against a smaller one, less than half of the soldiers will fight while the others wait in the back. No matter how many time you tell them to attack, they never fully engage the enemy. This makes some melees last much longer than they should and causes unnecessary casualties.

It should programmed so that the soldiers in the back of a formation move around the melee to find opponents.This is usually how it works in most strategy games, including some really old ones such as Warhammer or the
more recent Battle for Middle Earth.

Once again, to make it work in M2TW, you need to trick your units into it by giving a move order past the enemy unit and then giving an attack order. You lose a couple of soldiers while doing this, but in the long run it's better.

The same problem appears in melee involving many units, one unit will fight while the others wait in the back instead of trying to got around the melee to find enemies.

[Husar]

It may be because Medieval 2 controls units and individual soldiers don't have that much of an AI. I remember in MTW individual soldiers would follow individual routers but since RTW units chasing routers will keep unit cohesion(except for that bug that makes them spray around aimlessly) and are thus a lot less effective when chasing routers. That's just to give another example. bI agree that individual soldiers should show a bit more initiative in fighting and chasing.

[kawligia]

It worked well in MTW. I don't know how they went backwards like that, but they went backwards in a lot of areas. :(

[FactionHeir]

In M2TW it doesn't work by default, but you can help it by running the unit that is already engaged in combat through the opposing unit (you'll lose a few men that way however) and then click attack. Usually use this most in city battles.

[Miracle]

Cavalry will encircle enemies in exactly the way you described, but infantry won't.

Perhaps the reason why is that infantry would be exposed to counterattack, which they can't avoid as easily as cavalry.

For example, in your second image the black-colored units on the right would be a ripe target for a devastating cavalry charge from the Northeast direction. Mounted units can pull out and avoid the charge, but it's much harder for infantry to do this.

[Agent Smith]

The first picture I agree with. That's annoying.

But, in your second picture you can fix that by, say, moving the units to the flank and charging rather then sending them in one giant clump

[Durallan]

I think its done because back in those days the people at the back could see the people dying at the front and they was thinking, hey if I just hang back here, they might win and I won't have to fight for my life!

hmm who knows! not sure it is annoying but I gues they gotta have room to kill and stab each other.