Ave generals!

I was uding some sappers lately and I found them very effective and quick for destroing walls..
But I was wondering how would i defend myself if the opponent would use it against my walls ?
Would I need to sally fort or just burn them with firearrows? Do my archers have such range/is it possible at all? - they start digging quite far..

I must be prepared for the Brutii started to besiege me..
I`m now the faraon