Secret Avengers (2010 series) #11

The captive John Steele is at Secret Avengers headquarters where he has been hooked up to a machine that can read his memories—to find out how America’s first Super-Soldier ended up a villain. Beast, the machine’s operator, explains to Steve Rogers that the memories may be inaccurate and include gaps; Steve wants to proceed. They see Steele’s memories of the Civil War (US not Marvel), the Old West, World War 1 and 2. One of Beast’s assistants proposed that since Steve (as Captain America) was with Steele on his final mission, he be hooked up to a second console and their memories read together to provide a more accurate picture….

The mission was to assault a Nazi stronghold in a forbidding castle; Captain America takes out two guards with a toss of his shield while John Steele uses his super-strength to rip a heavy iron grating out of the wall to provide an entrance. Entering, they discover a lab where the Nazis are turning local villagers into huge Frankenstinian monstrosities. They are attacked by one such creature and it takes their combined skills (and a machine gun) to kill it. As Steele’s memories of the mission return, he becomes increasingly terrified and guns down Cap…

…which jolts Steve out of the machine. But John Steele is also free and he takes one of Hank’s technicians hostage….