These are an historical set of issues. The overall idea behind this series is to let Roger Stern write some 1940s Marvel stories. It’s awesome.
In these first issues, Baron Strucker gets his hands on some history books from the future (notably the seminal book on WWII, “The Rise and Fall of the Third Reich”), and tries to do what he can to change the course of the war. The Invaders fight him.
Most of it is unimportant (but very, very well done), but there are a few retconny things. Notably, Thor is introduced prior to his coming into existence on Earth in the pages of Journey Into Mystery.
As is Doctor Doom–but before he put on the metal mask!