I'm watching a bbc or H channel documentary series decisive battles and came to think how close with computers of 2009 you could get to actual 1:1 scale simulations? This program was done in 2004 and uses rome total war for the 'simulation' which is more like a demo. If you could have modern computers and maybe even networked modern computers complete with water cooling etc. couldn't you actually have a battle with 70.000 soldiers on the field? This kind of game technology doesn't simulate everything perfectly but just the visual 1:1 simulation would be pretty impressive and I would think that historians might like the idea.