Paul was born on the 25th of March 1889, in Wichita, Kansas, and because of his father being a minister, he spent his childhood moving around and would end up in Idaho. He entered the University of Idaho in Moscow after graduating high school in 1906 and after one year, received an appointment to the US Naval Academy. While at the Academy, he reached the rank of Cadet-Commander and served as Commander of Midshipmen Battalion, graduating in June of 1911 with a Bachelor of Science degree. Paul was commissioned as an Ensign one month later and was on board the USS Utah, under the command of Captain William Benson, when it was ordered to intercept a German-flagged steamer that was en route to Mexico. When the steamer arrived in Vera Cruz, the US officially began the Mexican Campaign, and it was Paul’s actions during those two days that would later earn him the Medal of Honor. The citation reads:

For distinguished conduct in battle, engagements of Vera Cruz, 21-22 April 1914. In both days' fighting at the head of his company, Ens. Foster was eminent and conspicuous in his conduct, leading his men with skill and courage.

Following the campaign, Paul transferred to New London, Connecticut, for submarine training and upon completion he was assigned to the USS G-4. This was an experimental submarine that he served as the executive officer for a year before taking over as the commanding officer. When the US entered into World War 1, Paul requested to be assigned to a European war zone but his request was turned down by his old commanding officer, now Admiral William Benson. By July of 1917, he was temporarily promoted to Lieutenant and served as a submarine tender and then navigator on the USS Bushnell, before serving as an aide to the chief of staff to the commander, Submarine Force, Atlantic Fleet. Paul was then the commander of the USS L-2 when patrolling Atlantic waters in July of 1918 and when a German submarine was spotted (initially thought to be a buoy) and Paul lined up the L-2 for a torpedo shot. Before any command or action could take place, the German submarine, now known to be the SM UB-65, exploded and sank with no survivors or bodies recovered. For his actions during this event, Paul received the Navy Distinguished Service Medal and was temporarily promoted to Lieutenant Commander.

After the War, Paul traveled to the Philadelphia Navy yard and was appointed to the USS Trenton’s engineer officer and sailed to the Mediterranean Sea for a shakedown cruise. In October of 1924, the Trenton was participating in gunnery drilled near Norfolk, Virginia, when the powder bags in the forward turret exploded. Every member of the gun crew was either killed or injured in the explosion and Paul entered the turret and extinguished the fire. He received the Navy Cross for these actions and once the ship was repaired, both he and the Trenton sailed to Guantanamo Bay, Cuba. In 1929, Paul resigned from active duty and spent ten years in the US Naval Reserve and spent time with various civilian organizations and traveled to the Galapagos Islands for a resource survey with the Pacific Development Company. He was recalled to active duty when the Japanese bombed Pearl Harbor and while he did not participate in combat during World War 2, he performed many logistics duties and was promoted to Rear Admiral and appointed to be the Assistant Naval Inspector General in August of 1943. Paul retired and was put on the inactive list in October of 1946 at the rank of Vice Admiral after 23 years of active service.

Now a civilian, Paul became the vice president of Mandel Brothers, Inc in Chicago and held this position until late 1950. He was later appointed Special Assistant to General Manager for International Activities for the Atomic Energy Commission, later becoming the acting General Manager in 1957. President Eisenhower appointer Paul to be the Permanent US Representative to the International Atomic Energy Agency in Vienna, Austria, and he officially retired in April of 1961, in Virginia Beach. Paul Frederick Foster died on the 30th of January 1972 at the age of 82 and he is buried with his wife, Isabelle, in Arlington National Cemetery: Section 5, Lot 106. Four years after his death, a Spruance-class destroyer was named in his honor: the USS Paul F Foster (DD-964).