Lincoln Leslie Loper served in France with a military medical unit during the last year of WWI.  Born and raised in Iowa, Loper  eventually worked his way to Washington, living in Seattle as early as 1942.  It’s tough to trace an individual based on scant information, but I’ve been able to deduce that he passed away in 1972 based on his military records.

Lincoln L. Loper in a Gas Mask, 1919

Lincoln Loper Postcard Backside