Does size matter?

[Imp]

A hint here when defending on big maps you do not need to defend everything just the objectives & your arty park. By all means have people out on flanks or forward to cause delays & see whats coming but more often than not pull them out soon after contact & either move them to bolster your main force guarding the flags or position them for an ambush or some such. This slows the attack catching him off guard may well draw arty & can give the impresion you have more forces than you actualy do.
If he sends some people to deal with you they have done there job there is no need for them to stay & get outnumbered.
As you are defending gaining the initative is not really possible but you can throw him off by making him wonder what you are up to which is the next best thing.
Lose control of the battle & you have probably lost it full stop.
Don't set up close enough though that you are a prime arty target you want good interlocking fire & surviverbility to make him pay.