Sadly, you cannot play Creative Assembly's Total War games on an iPad. What you can now do, though, is play an iPad game by the same developers, which has almost nothing in common with the series with which it shares a name, but is still worth a look.
Total War Battles isn't an attempt by CA to bring the Total War experience to a tablet. It's instead an attempt by the team to create something new, a blend of puzzle game and RTS that makes the most of the platform while still keeping things quick and simple enough to be able to play in short bursts.
It doesn't work entirely - it feels a little too much like a puzzle game at times - but for the most part this is a fun and unique take on strategy for the iPad. It also looks great. As a bonus, it shares Total War: Shogun 2's amazing soundtrack.
Total War Battles [$6.99, iTunes]