Captain America #115

The Red Skull appears in the disguised Steve Rogers' rented room via the Cosmic Cube. After roughing Steve up, the Skull uses the Cube to change Steve into Captain America, and they start to fight. With the Cube, the Skull holds ultimate power and is able to subdue Cap. The Skull recounts the story of how he came back into possession of the Cosmic Cube and then forces Cap into a warped reality far from the one he knows. As Rick Jones searches for Cap in vain, Cap is holding onto his sanity despite the best efforts of the Red Skull. The Skull decides to use a different tactic: he conjures up Sharon Carter in order to distract him. The Red Skull then switches bodies with Cap, and thanks to the Cosmic Cube, the Red Skull is now Cap...and Cap is now the Red Skull.