Rin Tin Tin was a German Shepherd puppy rescued from a bombed-out kennel in France during WWI by American soldier Lee Duncan. He became one of Hollywood's biggest stars in the 1920s, and his movies helped make the breed hugely popular in the US.
Anti-German feelings after WWI led the AKC to drop "German" and call the breed simply the "Shepherd Dog," and in Britain it became the "Alsatian." The AKC restored the original name in 1931, while the UK Kennel Club didn't fully return to "German Shepherd Dog" until 1977.
During WWI, the Dachshund's German roots made it unpopular in the US, and some people even rebranded the breed as "liberty pups" to dodge anti-German feelings.
The Bulldog is the unofficial mascot of the US Marine Corps, connected to the legend that German soldiers called Marines "Devil Dogs" during WWI. A Bulldog named Chesty serves as the mascot at Marine Barracks Washington.
During WWI, France began building a fake Paris outside the city with lights to trick German bomber pilots.
Ernest Hemingway was an ambulance driver in World War I and was wounded.
J.R.R. Tolkien fought in the Battle of the Somme.
Claude Monet donated his giant water lily murals to France as a monument to peace after World War I.
The phrase "pushing up daisies" became popular during WWI.
During World War I, Marie Curie created mobile X-ray units, nicknamed "little Curies," to help treat wounded soldiers.