Ordering Archers to Attach Enemy Archers ???

[rsolow]

What happens if there are no enemy archers (or no enemy flyers, if "attack flyers" order was given)? Are my archers "smart" and know to default to attack closest?

[PDF]

Yes they switch to another target, usually closest.

[Arralen]

You shouldn't order them to "attach archers" , as this will make the charge them to kill them in melee.
Better order them to "fire at: archers". They will switch to another target ( : nearest) as soon as there is no more valid pre-set target, e.g. no archers, or all enemy archers routing.