Tales of Suspense #66

Senator Byrd has come to audit Stark's factory. He is displeased that Stark kept him waiting. Happy decides to impress Pepper by offering to test Stark's new submarine. Tony insists that Iron Man does the testing. Happy leaves feeling disgruntled. Under the sea, Iron Man in the sub stumbles across Attuma who is preparing to attack the surface world. They battle. Iron Man destroys Attuma's weapon by ramming it with the sub. Iron Man survives the resulting explosion and has to explain the failure of the test to Byrd, who is highly critical of Stark. Happy, meanwhile, is nowhere to be found.