Farm Enigma codes in the quickest and easiest way possible in order to acquire :

Prior to accepting this mission you need to be prepared to :

Finish the game
Wait for the obnoxious end credit rendering of We're Not Gonna Take It to finish
Commit a couple of hours of your time
Be disappointed

Luckily this process only take a few seconds to complete each time.

After you have killed all the available Ubercommanders the location of the final one will be revealed :

Unfortunately it requires another 8 Enigma codes, so get your ass back to Venus again.

So what are you waiting for ?, Liberate America and make Der Führer cry.