Robert was born on the 18th of August, 1887, in Pittsburg, Pennsylvania, and he joined the US Navy in 1906 at the age of 19. He was a Chief Gunner during the Mexican Campaign where his actions would earn him the Medal of Honor. The citation reads:

For meritorious service under fire on the occasion of the landing of the American naval forces at Vera Cruz on 21 April 1914. C.G. Semple was then attached to the U.S.S. Florida as a chief turret captain. (CMOHS.org)

Robert remained in the Navy and served during World War 1, where he received the Navy Cross for his actions in the North Sea minefields. He retired from the Navy in 1937 as a Lieutenant Commander but was recalled to service in 1941 for World War 2. Robert Semple died on the 13th of May, 1943, while on active duty and he is buried with his wife Mabel in the Fort Rosecrans National Cemetery in San Diego, California: Section OSA, Site 192 (FindAGrave.org).