Frank J. Sarris was born on December 8, 1917, in Newport, Rhode Island, in the USA. His parents were Greek immigrants, John Sarris and Maria Lafiotis, both originally from the beautiful island of Skiathos. Frank's father first arrived in the USA between 1900 and 1905 to obtain American citizenship. To achieve this, John Sarris volunteered for the U.S. Army during World War I, serving in France with the 6th Engineer Regiment before returning injured to the USA. In November 1915, he married Maria in Providence, Rhode Island, and later, after moving to Newport, they had four children: Rose (1916), Frank (1917), Koula (1919), and George (1922). Frank enlisted in the Rhode Island National Guard and served three years before being discharged. He then reenlisted in the National Guard for another four months before joining the U.S. Navy on November 1, 1939, as a "Seaman Apprentice" with a prospect of six years of service. In January 1940, he was assigned to the aircraft carrier USS Ranger (CV-4), where the impressive sight of aircraft taking off and landing on the flight deck profoundly influenced young Frank. Due to the needs of the war, the Navy's requirements were reduced from the required two years of college or university studies, allowing Frank to apply for pilot training. On January 5, 1943, he reported to Pre-Flight Training School at the Naval Air Station in Athens, Georgia. On October 12, 1943, after completing all tests, Frank was designated an "Aviation Pilot 1st Class" and a few days later proudly wore the "Gold Wings of a Naval Aviator." He underwent training on Wildcat aircraft and qualified as a pilot capable of operating from aircraft carriers at NAS Glenview and then received further training on the more advanced F6F Hellcat.

On May 17, 1944, he reported for duty with VF-37, which belonged to Air Group 37, operating from the aircraft carrier USS Sangamon (CVE-26). His initial missions were carried out during operations in the Marianas Islands, where the Americans inflicted significant losses on Japanese naval aviation in a series of air battles that became known as "The Marianas Turkey Shoot." Unfortunately, for the pilot of Greek descent, VF-37 was assigned to cover specific forces of Task Force 52 and did not engage with Japanese aircraft. On July 10, the invasion of Guam began. Sarris and his fellow pilots provided air cover for the American forces on the island, conducting escort missions for bombers. Although they did not engage in large-scale aerial combat, their main tasks were strafing missions since the USS Sangamon was a reserve carrier. Frank logged several flight hours, and he completed ten combat missions. He returned to operations during the American invasion of Leyte in the Philippines. On October 18 and 19, 1944, just before the landings on Leyte Island, the carrier-based pilots, including Sarris, conducted a series of pre-strike attacks against Japanese airfields and various other installations in the Leyte and Visayan Islands. In the early morning of October 24, Sarris sat in the cockpit of an F6F-5 Hellcat as part of a four-aircraft patrol (CAP - Combat Air Patrol). At 07:45, the signal for take-off was given, and the four Hellcats headed for their CAP station. A few minutes later, they spotted a mixed group of aircraft consisting of 4-5 twin-engine Kawasaki Ki-48 Lilly bombers and Mitsubishi Ki-21 Sally bombers heading towards the American ships concentrated in the Leyte Gulf. The Grumman fighters encountered the enemy formation and selected their targets. Three bombers were shot down, one Lilly by Sarris himself. On the morning of October 25, 1944, during the battle in the Surigao Strait, Frank attacked an enemy destroyer. Shortly after, as a member of a nine-aircraft formation targeting the Japanese cruiser IJN Suzuya, with a displacement of 13,670 tons, he caused damage with his gunfire, paving the way for the bombers and torpedo planes to strike. As the battle continued with unabated intensity, the VF-37 pilots were forced to break off their attacks due to the appearance of a Japanese fighter force consisting of approximately 10 Mitsubishi A6M Zero and Nakajima Ki-43 Oscar fighters. The VF-37 F6F-5 Hellcats, having gained the advantage of altitude and surprise, engaged with five of the enemy aircraft while the rest disengaged. The American planes shot down five enemy interceptors and two others as probable, with Sarris downing one Ki-44 Tojo, out of the two that rushed to support the Zeros and Oscars, and another Zero as probable. The critical fuel situation forced them to land at Tacloban Airport in the interior of Leyte, which had recently been captured by the Americans. Subsequently, Frank returned to the United States, and on February 16, 1945, he was promoted to Lieutenant.