Re: Universal battle-winning strategies
Use two missile units to create a cross fire on a single unit. This is not quite a flanking move, but should break most units. Crossbows are very effect with this method.
All units have their use at various stages of the game. For example, Peasant archer units lack penetrating power, but are the very backbone of your offense on turn one. Even later in the game, flaming arrows can still eliminate seige towers and rams.
Keep units organized and in line for open field battles. Breaking line formations before the eney breaks will lose the strength of your attack.
In forrested "open field" combat, it is very difficult to maintain lines. Even the computer will break lines upon advancing. This is an opportunity to flank individual and small groups of units. Missile crossfire is also now more effective. Keep your units in formation.