The fact that the super hero concept is not working out, sales-wise, is made clear by the cover of Blackhawk 239 (Feb/March 1968), which puts the heroes back into their military outfits, and even features a giant swastika.
The Blackhawks are busy in their iceberg hideout, which seems extremely roomy. Lady Blackhawk is visiting them, but does little in the story, aside from having a golden statue made of her.
While the real Blackhawks are goofing around and wasting time, impersonators have gone to a village in the Alps, intending to steal a sword. The townspeople believe these are the same men who liberated them during the war. As does a Nazi, nicknamed the Iron Hammer, who had been frozen in the ice for like 20 years. He emerges and just happens to come to the town at the same time as the fake Blackhawks, and kills them.
The real Blackhawks get alerted about this, and head out to the town. There is a brief flashback sequence to their battle back during World War 2, but most of this takes place in the present day, as the Iron Hammer tries to kill off the Blackhawks, as they hunt him in the mountains.
The Blackhawks allow the Iron Hammer to think he has killed them all, but they just get into their old outfits and show up as the old Nazi goes to a ruined temple-ish thing with a giant swastika. The Blackhawks show up, and basically scare him so much that the villain winds up killing himself accidentally.
It's not like this is much of an improvement over the super hero stuff.