First Appearance: New Mutants #86 (March 1990).
Appearances: Too many to count.
Years Active: Various (see below).
Okay, look. You might like Cable, you might hate him. But he's one of these time travelers, and he's been shown to have fought in a number of different wars. I \think World War Two is too large and too obvious a conflict for him not to somehow have been involved in. I know that his war against Apocalypse is his obsession and driving force, and that Apocalypse has never been shown as having anything to do with WW2, but that doesn't mean Cable couldn't have been involved, somehow, in fighting against the Axis.
Since first posting this I've been informed that Cable's purpose in coming to this time was to stop the ascension of the Externals, and that it was the "chronal disturbance" of his arrival in our time that awoke Apocalypse, and that therefore he wouldn't have any reason to go to WW2 and that if he did, wake up Apocalypse. Fair enough. I'm going to leave the possibility open, however, because I think it's neater that way.