Gold Star Mothers organization in 1932. There are ten women somewhere among the 700 men listed.
The dates require a little explanation for those of us for whom the "Great War" is distant history, especially since we can expect to hear about the 100th anniversary of that war in the next few months.
The April 6, 1917 date is when the U.S. plunged into the European conflict that then had been raging for two years. On July 2, 1921, President Warren G. Harding signed a proclamation declaring the war terminated, although the United States never ratified the Versailles Treaty by which the victorious British and French had redrawn the map of Central Europe and what we call the Middle East. World War II (1939-45) and the collapse of the Soviet empire (1989) redrew many of those European boundaries. Very likely, the lines imposed further east are now coming unstuck.
There's no path or sign that points to this monument from roads in the park. If you don't know it is there, you'll only come upon it by chance. The park website only refers to it obscurely as Heroes Grove and barely mentions this massive marker.