Walter was drafted on 29 Mar 1918 and first reported to Camp Custer. Before leaving there he would marry Anna Cornelia Dees on 1 May 1918. His wife would visit him at Camp Custer before he was transferred to Camp Gordon, Georgia and then to Camp McClellan, Alabama where he was assigned to K Company 116th Infantry. He traveled to France with that unit, departing Hoboken, New Jersey on 15 Jun 1918 aboard the USS Finland and arrived in France on 28 Jun 1918. According to newspaper reports of his death, he was assigned to the intelligence section working in the Alsace sector for 2 months and then to the Meuse-Argonne sector, just north of Verdun, for 21-days. He was then sent to the Lisle eu Regault where he became ill with the measles on 11 Nov 1918. He was evacuated to Field Hospital 116 and from there to Base Hospital 83 where he died of meningitis.
PVT Wissink was repatriated in 1921 and re-interred in the Cedar Grove Cemetery in Cedar Grove, Wisconsin.
Anna and Walter had no children. Anna re-married in 1921 and had several children with her second husband.