From 1939 to 1941, Oldendorf commanded the cruiser . In September 1941, he joined the staff of the Naval War College, where he taught navigation until February 1942. On 31 March 1942, Oldendorf was promoted to rear admiral, and assigned to the
Aruba-
Curaçao sector of the
Caribbean Sea Frontier. In August 1942, he was transferred to the
Trinidad sector where
anti-submarine warfare was his primary duty. From May through December 1943, Oldendorf commanded
Task Force 24 which was assigned all Western Atlantic escorts. His flagships during this period were
destroyer tender and fleet tug . At this point in his career, Oldendorf was an experienced battle commander who had handled similar assignments in three previous Marine landings. The bombardment was scheduled to last three days. By the end of the first day, aerial reconnaissance photos indicated that close to 300 of the assigned targets had been destroyed or seriously damaged by the all-day bombardment and that virtually every aboveground structure and fortification had been eradicated. At the airport its few usable planes were reduced to wreckage. After the war when asked about Pelilieu, Oldendorf commented that "If military leaders – and that includes Navy brass – were gifted with the same accuracy of foresight that they are with hindsight, then the assault of Peleliu should never have been attempted." ,
Honshū,
Japan. On 24 October 1944, Oldendorf was the commander of
Task Group 77.2 at the
Battle of Surigao Strait. From aboard his flagship USS
Louisville he led the defeat of the Japanese Southern Force. He deployed his powerful force of battleships and cruisers in a classic battle line formation across the
Surigao Strait,
crossing the T of his opponent. The Japanese battleships and were sunk, and
Vice Admiral Shoji Nishimura was killed. Oldendorf's action prevented the Japanese from bringing their battle fleet into Surigao Strait and attacking the beachheads on Leyte Island. He later explained his tactics to the
New York Times: "My theory was that of the old-time gambler: Never give a sucker a chance." For this action, Oldendorf was awarded the
Navy Cross. In 1959 Admiral Oldendorf provided commentary on his planning for the battle: On 15 December 1944, Oldendorf was promoted to
vice admiral and made commander of Battleship Squadron 1. He was wounded breaking his collar bone at
Ulithi on 11 March 1945, when his barge hit a buoy. Oldendorf assumed command of
Task Force 95 in July, and led this force on two sweeps of the
East China Sea. He was wounded, breaking several ribs, when his flagship
Pennsylvania was torpedoed by a Japanese aircraft on 12 August 1945. On 22 September 1945, Oldendorf commanded the occupation of
Wakayama and dictated terms of surrender to Vice Admiral Hoka and Rear Admiral Yofai. ==Post-World War II life==