W. Pinger was killed while serving in the US Army during World War I while serving as a First Lieutenant in A Company, 16th Infantry Regiment, 1st Infantry Division.
From Find Grave:
First Lieutenant Walter Louis Pinger
Battalion Scout Officer, 1st Battalion, 16th Infantry, First Division. Killed in action near Yoncq, Meuse, on November 7, 1918.

Lieutenant Pinger was born in St. Joseph, Missouri, on January 28, 1896. He was educated in the public schools of that city, graduating from high school and then taking an electrical engineering course which he gave up to enter the Second Officer's Training Camp at Fort Sheridan, 2nd Company, previous to which he had undergone three months training at Fort Riley, Kansas. Receiving a commission as second lieutenant at Fort Sheridan, he was ordered overseas, sailing as a casual on December 20, 1917. Arriving overseas, he was given further military instruction until April 1918, when he was ordered to the Seventy-eighth Division, remaining with the 309th Infantry until August, at which time he was transferred to the 16th Infantry. On October 10th he was severely wounded by machine gun bullets in the successful attack on Hill 272. After a period in the hospital he returned to duty as a scout officer and on November 7, 1918, he was instantly killed by shell fire during the Meuse-Argonne offensive. Lieutenant Pinger was cited for bravery and promoted to a first lieutenancy on October 26th. He was unmarried. His parents, Mr & Mrs William R. Pinger, 3115 Edmond St., St. Joseph, Mo., survive.
(taken from The Fort Sheridan Association p. 136)