The Captain America to fight Nazi Sentinels in the Second World War. In the aftermath of 2012's "Avengers Vs. X-Men" event, Marvel launched an ongoing series called A+X in which - rather than fight - random X-Men and Avengers were working together. It was an anthology book, and it contained some tremendous short stories.
The first issue featured a story by legendary Spider-Man scribe Dan Slott, in which he brought together Captain America and Cable. The story was set in 1943, with Steve Rogers receiving new orders after the Nazis began work on a massive dig in the French countryside. Adolf Hitler had a new "wunderkind," a scientist named Atticus Trask, and he was working on some sort of vengeance weapon. All the top brass knew was that Trask would put it to sleep now, dormant, only for it to return to wreak havoc at a later date.
Captain America and Bucky successfully infiltrated the dig, and were taken aback to see what readers recognized as proto-Sentinels putting the finishing touches to a Master-Mold unit. The two were planning to use guile and subtlety to plant explosives and destroy the Sentinels, taking Trask out before he could construct any more; that was when their mission was interrupted by the time traveling Cable.
Atticus Trask was a time traveler as well, and he had been jumping through the timestream in an attempt to change history and wipe out the entire mutant race. He'd taken a pit stop in 2099, briefly losing Cable, but the Askani'son had successfully tracked him down again. It seems Trask was manipulating Hitler, because his Sentinels were programmed to awaken centuries earlier and kill the X-Men's first class - and Charles Xavier - before the team could be founded. Needless to say, the partnership between Cable and Captain America was successful; the Sentinels were destroyed, and Trask was captured, spirited away by Cable to an unknown fate.
Cable attempted to keep the future secret from Captain America, fearing the timeline would be changed. He'd forgotten how intelligent Cap is, though, because he did give away one simple fact; that the Allies would win the war. Steve Rogers noted that Cable was speaking English, whereas he'd be talking German had the Nazis triumphed. No doubt Captain America thought this was a major "spoiler," but he had no way of knowing what other secrets Cable could have revealed had he wished.
