Magazine covers during summer 1919, after WWI had ended, were different than during summers 1917 and 1918 during the war:

For two Summers the June, July, and August covers displayed about the same thing that they showed in the other three seasons — beautiful girls dressed as nurses, or canteen workers, or motor corps drivers, or Salvation Army maids.

…

However, the girls have taken off their uniforms. The war is over. There is a rush back to beach costumes on the front covers.

Of course, the one similarity both during and after the war is that the magazine covers still featured posing “girls.” But at least they were wearing something — the first issue of Playboy wouldn’t be published until December 1953.

If You Don’t Believe the War Is Over — Look at These Summer Magazine Covers (PDF)

Published: Sunday, July 20, 1919