A member of the Rhode Island National Guard, Case was called to active duty on June 14, 1916 and served on the Mexican border as captain of Troop A of the 1st Cavalry Squadron until the unit was mustered out of Federal service in November. Shortly after the United States entered World War I in April 1917, Captain Case and his troop were mustered into Federal service on July 25. On August 20, Case's troop was re-organized as Company A of the 103d Machine Gun Battalion which was assigned to the 26th Division. He sailed for Europe on October 2 and served in France with his unit. He was reassigned as Judge Advocate of the 26th Division on January 1, 1918 and as Assistant Provost Marshal for the Services of Supply on February 13. He was reassigned to the administrative section of the Headquarters of the Services of Supply on August 11 and to the supply section on April 20, 1919. He returned to the United States on July 17, 1919 and was discharged two days later. He was awarded the Order of the Black Star of Benin by the French government in recognition of his service. Case remained a city councilor during his military service.
Political career
appointed Case U.S. District Attorney for Rhode Island in 1921; he left the position in 1926 to run for Lieutenant Governor. He won the election, taking office in 1927; just over a year later, on February 4, 1928, Governor Aram J. Pothier died in office, making Case acting governor. Case won the governorship in his own right in 1928, and was reelected in 1930. Case was soundly defeated by T. F. Green in his 1932 bid for reelection. This election marked a tidal shift in Rhode Island politics from being predominantly Republican to being predominantly Democratic. President Franklin D. Roosevelt appointed Case as one of the initial commissioners of the Federal Communications Commission when that agency was set up in 1934, and reappointed him for a full seven-year term in 1938. In 1945, by-then Senator T. F. Green opposed Case's candidacy for a third term, and President Harry Truman did not renominate him. Case was succeeded on the FCC by former Vermont governor William H. Wills. After leaving the FCC, Case returned to private law practice, joining Frank W. Wozencraft, former general counsel for RCA, in the Washington firm of Case & Wozencraft.