Help with archers and artillery.

[Matty]

Simple - general killing.

Good artillery especially, but also archers, can take out a general that can in some cases pancake morale in the remaining army.

Defensively, especially at a bridge, they are devastating. In an open field battle archers are less effective but the concentrated firepower of three or more cannon can really take the wind out of massed enemy troops. When the first lines engage you can continue to pummel the enemy by firing over their heads.

[Ramses II CP]

There are some excellent archer units in the game. As the English I often field armies of just a general and Yeoman or Retinue longbowmen. The enemy has to come to you, because of your range superiority, they can't effectively charge through your stakes even if they aren't a cavalry unit, and just by wrapping one unit on either end of your line you'll break the moral of any of the much reduced troops that make it into melee.

When they break and rout, your arrows go in their unshielded backs, and few of them will make it back out of range. If you want to annihilate an enemy army, bring a full stack of Yeomen or RLs.

As a general rule, though, I don't use bow units that can't at least be used effectively in a melee as a flanker. Peasant archers are IMHO, as noted, only good for a few volleys of fire arrows and soaking enemy arrows up.