Jacob Walter Feigenbaum was born in Missouri on April 2, 1911, and had at least one sister, Jeanette. Their mother Rose was a Russian immigrant and their father was born in Austria. Jacob, most frequently addressed as "Walter," enlisted in the United States Army before February 1944 and trained at Fort McClellan, Alabama, before being deployed to Europe in the summer of 1944. While in Europe, he became a member of Company C of the 117th Infantry Regiment. His mother and sister lived in Washington, D.C., during the war, where Jeanette worked for the Federal Communications Commission. Jacob Walter Feigenbaum died in Montgomery County, Maryland, on February 25, 1995.
From the guide to the Jeanette and Rose Feigenbaum letters, Feigenbaum, Jeanette and Rose letters, 1944, (William L. Clements Library, University of Michigan)
