Searching for an RTS style game

[Ipaduser123]

Are there any games.. Preferably Free that are RTS for the iPad? What I mean by RTS are similar to the command and conquer games, or even the warcraft type games. Something where you can build and attack thats endless fun as I have an ipad but yet to find a fun or decent enough game to keep me entertained primarily during class.
Let me know any help appreciated!