I for one have come to appreciate the use of archers on the offense. Their ability to fire over the heads of a wall of spearmen makes them really useful even on the offensive, even if managing two fairly long lines who are dependant on each other on the march can be troublesome in hilly terrain: you have to make sure your spear units have favourable ground while your archers are entirely protected - yet they also need a clear field of fire and mustnt become intermingled with the spearmen in front of them. Needless to say, this tactic works even better with longbowmen.
This allows you to maintain a steady line of battle that, while protected by the spearmen - who themselves can inflict great casualties upon the enemy in melee given that they have the right upgrades, valour etc - provides a constant rain of arrows to whittle the enemy forces. Having this stable line of fire established, your flanking units should be able to do the real work without much resistance.
Very true, although I usually bring a total of five or six units with an equal amount of polearms right behind them. Not sure if this is actually preferable to a lesser amount of arbs or not though... Probably not: offensive battles have nasty tendency to become sluggish, so generally more infantry would be of greater use.
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