Reinhardt Keppler was born on January 22, 1918, in Ralston, Washington. He enlisted in the U.S. Navy on February 19, 1936, and was trained as a boatswain. BM1 Keppler was serving aboard the heavy cruiser USS San Francisco (CA-38) at Pearl Harbor when the Japanese attacked on December 7, 1941, and later participated in raids in the Gilbert and Marshall Islands, the Solomon Islands Campaign, and the Naval Battle of Guadalcanal. Keppler died from wounds he received during the Battle of Guadalcanal on November 15, 1942, and he was buried at the Golden Gate National Cemetery in San Bruno, California.

His Medal of Honor Citation reads:

For extraordinary heroism and distinguished courage above and beyond the call of duty while serving aboard the U.S.S. San Francisco during action against enemy Japanese forces in the Solomon Islands, 12 & 13 November 1942. When a hostile torpedo plane, during a daylight air raid, crashed on the after machine-gun platform, Boatswain's Mate First Class Keppler promptly assisted in removal of the dead and, by his capable supervision of the wounded, undoubtedly helped save the lives of several shipmates who otherwise might have perished. That night, when the ship's hangar was set afire during the great battle off Savo Island, he bravely led a hose into the starboard side of the stricken area and there, without assistance and despite frequent hits from terrific enemy bombardment, eventually brought the fire under control. Later, although mortally wounded, he labored valiantly in the midst of bursting shells, persistently directing fire-fighting operations and administering to wounded personnel until he finally collapsed from loss of blood. His great personal valor, maintained with utter disregard of personal safety, was in keeping with the highest traditions of the U.S. Naval Service. He gallantly gave his life for his country.