These covers became a cliché of the war comics genre, starting in the late 1960s and extending well into the 1970s. Here's a classic example, from Our Army At War #195 (July 1968):
Here we see the classic elements of the DWTANEH cover:
1. Hidden enemies in the foreground.
2. Central "hole" in the cover through which we can see the approaching Americans.
3. Clear statement or belief that the enemies are not there.
Here are a few more examples:
As you can see, the covers pack some dramatic punch. The reader can see something that the approaching GIs can't, that there is about to be a sudden reversal of fortune. A number of these covers feature children, as in the GI Combat issue above, or this one:
The children may give an added sense to the soldiers that everything is okay, that they are not about to be ambushed. You can see the same thing with these covers:
These covers also often feature blinded American soldiers:
This adds a bit to the dramatic tension, as we know that even if the soldiers become aware of the enemy's presence, they will be hard-pressed to do battle.
Similar themes crop up in these covers:
I was unable to find a significant number of these covers prior to about 1968. The Our Army At War #159 cover with the nurse helping Sgt. Rock is from October of 1965, but even that one is arguably atypical, in that Rock is clearly alert and on guard. Similarly, I don't think this February 1960 cover counts:
Here's the exit question. Was the popularity of these covers inversely related to the popularity of the US military among comic-buying kids and teens? As the Vietnam War dragged on, there is little doubt that the image of our armed forces declined, especially after an event like My Lai. Did this give the readers of the time an added perverse enjoyment of covers featuring American soldiers heading into an ambush? Or am I reading too much into this?