Seleukos Helios
Chieftain
I also agree the Manhattan Project should be somehow changed. Even if you have a modest technological superiority over your opponents, chances are that by the time you have completed the Manhattan Project your main adversaries will have discovered fission as well (rocketry is usually one of the first modern-age techs any AI civilization researchs), and you will have gained nothing in terms of a military advantage. It should either become a national wonder or give one or two ICBMs upon completion.