Yesterday I finally went with my mother to see the title exhibit at the Elmhurst Historical Museum in Elmhurst, Illinois:
http://elmhursthistory.org/315/Exhibits
It will only last for two more weeks; I don't know if anyone here is in the locale or not.
What it shows, as might be expected, are reproductions of various Peanuts comics relating to Snoopy fantasizing about being a World War One air ace who is always failing to defeat the Red Baron. Also some videos and various toy artifacts. But also a genuine World War One uniform, and descriptions of how in Charles Schulz's childhood, stories and comics of World War One pilots had been popular. Schulz himself would become an infantryman during World War Two and meet fellow cartoonist Bill Mauldin.
Another surprise I got was that Snoopy's brother Spike would become an infantryman in World War One, and his sister Belle a member of the Red Cross (in the 1990's comics), and even Snoopy's mother would be depicted on a troopship with other beagles. Also the flu pandemic that followed the war would be referred to.