Force archers to melee

[AMD4EVER]

There are times when I want my cavalry archers to go straight into melee without having to run out of arrows before doing so. I see the AI is able to tell their cavalry archers to just charge into hand to hand combat even though they still have arrows. I'd like to be able to do the same but I can't find what command needs to be used to do this. Could someone help me out with this?

[Byzantine Emperor]

Hold down alt on the keyboard while telling your horse archers to attack. This is true also to any missile troops.

[Quillan]

It's also true in reverse. Alt clicking tells the unit to attack with its secondary weapons. For horse archers, that means the melee weapons. For pike units, it means swords. For legionarii, that means not to use pila but to go straight for the gladius. And in BI, it tells the generals to use their armor-piercing maces instead of lances.

[ByzantineKnight]

Turning Skrimish off helps too, or else they stop before they hit the other unit and effectively lose their charge bonus.

[Ciaran]

I believe with 1.5 skirmish gets turned off automatically when you order any ranged unit to melee.

And in BI, it tells the generals to use their armor-piercing maces instead of lances.

That´s not only BI. As a matter of fact, in BI there are a lot fewer cavalry units with two weapons, in RTW most cav units have a spear and a secondary weapon, though only the cataphracts have an AP mace.
I suppose CA made less use of the secondary weapon in BI when they realized that this feature doesn´t work as intended (spear for the charge, secondary weapon for the melee).

[Ludens]

It's also true in reverse. Alt clicking tells the unit to attack with its secondary weapons. For horse archers, that means the melee weapons. For pike units, it means swords. For legionarii, that means not to use pila but to go straight for the gladius. And in BI, it tells the generals to use their armor-piercing maces instead of lances.

Also, if you want the archers of war and armoured elephant to shoot at a target without the elephant charging, use alt-click as well.