A Very Noteworthy Issue of Action Comics
This is an issue of Action Comics that is often overlooked when people talk about Superman's career, however it is actually very noteworthy for a number of reasons;
It all begins with the cover - this cover, while not particularly noteworthy for it's art, is the first time the DC circle logo appears on a comic cover.
Next, the city that Clark and Lois are from is named ' Metropolis' (previously it had been Cleveland, Ohio) and the 'Daily Star' is now referred to as ' The Daily Planet'. The reasons for the change to fictional names is unclear, but it seems that D.C. was concerned about the ramifications of using the name of another publication (there were several papers called The Daily Star at the time) in their own publications.
But it doesn't stop there - this issue also marks the first appearance of Luthor. And Luthor's plot seems to draw the story very close to real world events. Remember that this was 1940 and WWII had already begun in Europe, even though the U.S.A. was not yet directly involved. However, the events there seemed to clearly be on Jerry Siegel's mind. Continuing from last issue, Clark and Lois are in Europe reporting on a war there. Luthor is behind the scenes trying to agitate the situation and draw the entire continent into a war which will weaken all the nations and allow him to step in and assume control. The soldiers of Gallonia wear uniforms that resemble the German army, and one of the characters, General Lupo of Gallonia, a pawn of Luthor's, even sports an Iron Cross on his uniform.
Superman for his part also seems to have adopted a war time mindset - while he's always been fairly casual up to this point about injuring and killing people, never before has his body count quite reached the numbers in this issue where he hurls mortar shells at one army, fires a machine gun at Luthor's pilots, and destroys a dirigible full of people. At one point he even grabs a man and holds him over his head stating, "Either answer my question, or have your brains dashed out against that wall!".
So here we are in early 1940 and it's already clear that the Superman of the 40s is going to be a little different from the Superman of the late 30s.
(by E.Tragedy - Comicvine's original back issue reviewer)