He was most notable for his service as Third Army's Intelligence officer (G-2) under General George S. Patton in World War II.

When his unit was federalized for World War I as part of the 32nd Division, Koch served in France and received his commission as a second lieutenant of Field Artillery.

After the war, Koch returned to Milwaukee, where he was one of the re-organizers of his old Wisconsin National Guard unit, which he commanded as a captain.

Koch slowly advanced through the ranks in the 1920s and 1930s, and developed a positive reputation as an instructor and academic, primarily as a member of the faculty at the Army's Cavalry School at Fort Riley, Kansas.

During World War II, Koch joined the staff of George S. Patton's 2nd Armored Division as Intelligence officer (G-2).

After retiring, Koch resided in his wife's hometown of Carbondale, Illinois, where he was active in several civic and fraternal organizations.

He also authored a brief memoir of his World War II service, which continues to be used as a guide for Military Intelligence professionals.

[13] In 1931, Koch was named the Signal Corps instructor for the South Dakota National Guard and assigned to Watertown.

[16] Koch graduated from Fort Riley's advanced course for Cavalry officers in 1933[4] and remained at the school as an instructor.

[17] His work was reviewed by a doctoral committee and accepted as a dissertation, but Koch did not receive academic credit because he was auditing courses, not attending as part of a degree program.

[7] During the North African campaign, Koch served as chief of staff for one of Patton's subordinate task forces, Blackstone, which was commanded by Ernest N.

[7] Though G-2s at other commands believed Germany incapable of a large scale offensive, Patton heeded Koch's warning and incorporated emergency measures for aiding First Army into his subsequent plans.

[7] Third Army's effort helped end the German offensive and left the Allies prepared to enter Germany in the spring of 1945.

In 1946, he was appointed deputy commandant of the Army's new Ground Forces Intelligence School at Fort Riley, Kansas.

[7] He also served on the city government's Citizens Advisory Council and was a trustee of Carbondale's First Christian Church, an affiliate of the Disciples of Christ.

[1] In August 1924, Koch married Nannie Caldwell (1898–1995), whom he met while he was participating in a horse show at the Iowa State Fair.

[31] In addition, in 1993 the United States Army Intelligence Center named one of its buildings Koch Barracks.

[31] Koch received a 1954 Guggenheim Fellowship, which he intended to use to author a work on the conduct of military intelligence activities.