Does "doubling up" help?

[derF]

By this, i mean when you do something like place one unit of your phalanx on top of another. Thus, in the same space, you have double the units (and double the pikes!)

Does this work in the game in favour of combat?

[Dutch_guy]

I think it does, it definatley doesn't give penalties to attack or something like that.
That's probably why so many people cav. spam on the net. , they just form a blob with cav. and they don't even get neg. attack / armor something,

[derF]

cool.

Would it make them more vulnberable to missile attacks?

[Lord Preston]

not more vunerable but they are more likely to hit by arrows,

if your using heavy armored units dont worry about it, if unarmored (ie archers) dont even think about stacking.

personally i dont use this, cpu is stupid enough without exploiting it and online its just unfair.

enjoy

[Mikeus Caesar]

if unarmored (ie archers) dont even think about stacking.

You shouldn't even think about stacking archers, or putting them too close to the rear of another unit, or you'll get incredibly horrid FF.

[derF]

Nah, i need to use it against those pesky Egyptian and Scythian chariots.

[Craterus]

Scythia doesn't have chariots, I believe you mean Scythed Chariots.

[Uesugi Kenshin]

In cities it is vital, but otherwise it usually makes your units too easy to flank unless you can use a bridge or other feature to block flanking.