He was in the United States Army during World War II from June 1941 to April 1946.

In November 1942, he was stationed at Camp Stoneman in California where he remained until separating from service in December 1945 as a major.

[1] In September 1943, he completed the Command and General Staff School in Leavenworth, Kansas and was promoted to major.

[2] Upon completion of the Command and General Staff School, he returned to Camp Stoneman.

[3] On December 2, 1971, Dier was nominated by President Richard Nixon to a seat on the United States District Court for the District of Nebraska vacated by Judge Richard Earl Robinson.