Siege units in MTW2

[Encaitar]

One way of limiting the extent of artillery in (sp) battles would be to give artillery a dramatically reduced per-turn campaign map movement than infantry (and of course less again than cavalry). So if you want to bring artillery/siege weapons to a field battle, you're going to have to crawl across Europe to do so. I know it's there to an extent in R:TW, but it could be more.