Apologies for the long title, but I'm trying to find this old game from my childhood I've forgotten the name of.

It has a turn based view of the world with real time battles and allowed you to primarily play as all the major nations of WW2; UK, USA, Germany, France, Italy, Russia and Japan. There was diplomacy and the ability to change the course of history. The cover had the leaders of each faction all lined up with a dark background and a light over their faces.

Apologies for being so vague - that's sort of why I need help. Thanks, hope someone can help.

shouldn't be to hard

how old where you approximately ? or better asked which year did you play the game ?

Hm,...maybe this one?
https://www.gog.com/game/strategic_command_european_theater
it has (some of) the world leaders before a dark background. (see attachment)

Edit: of course - this is only the European theater...but there are more games in the series, though I don't know if those feature the world leaders in a similar way.