USS NASHVILLE (CL 43) carried General MacArthur on his return to the Philippines, for which she sailed from Manus on October 16, 1944.
She provided fire support for the Leyte Island landings on October 20, and she remained on station at the mouth of Leyte Gulf until October 25, guarding the troops on the beachhead and the nearby transports. Returning to Manus Island for brief repairs, NASHVILLE left the Admiralties on November 28 as the flagship for the Commander, Visayan Attack Force, en route to the invasion of Mindoro.

10.20.44 USS NASHVILLE Leyte Invasion Force - ULTRA
USS NASHVILLE during the Leyte Invasion Force

USS NASHVILLE also carried a Radio Intelligence Unit (RIU) lead by CDR Forrest “Tex” Baird from the Fleet Radio Unit Pacific FRUPAC, also known as Station HYPO.  Ironically the day of the Leyte invasion appeared not to be influenced much by the RIU afloat. Shipboard radio intelligence may have influenced the outcome of the battle even if the contributions of the RIU on the U.S. side were minimal. The Japanese Admiral Jurta explained his turnabout of Imperial Japanese Navy carriers was based on radio intelligence reports!  U.S. radio intelligence would play a significant role in disrupting the Japanese invasion of Ormac Bay in which many Japanese troop transports were destroyed and the Japanese strategy was disrupted.

Edward Drea (A) would write: “The Japanese high command operating on woefully bad intelligence gambled all at Leyte and lost. The American high command, acting on very good intelligence, took a well-calculated risk and won. Throughout the fighting on Leyte, ULTRA’s  (B) timely updates of the Japanese condition exposed the Imperial Army’s intentions and weaknesses. Without ULTRA, American GIs would have had to root out five well-conceived, well equipped, and well supplied Japanese infantry divisions. The killing would have rivaled the bloodiest scale of bloodletting on Okinawa and Iwo Jima. To ignore that fact overlooks ULTRA’s contributions.”

Note: The Battle of Leyte Gulf is generally considered to be the largest naval battle of World War II and, by some criteria, possibly the largest naval battle in history.

(A) Edward John Drea (born 24 February 1944) is an American military historian. He deals especially with the Imperial Japanese Army and the Pacific War.

(B) Allied intelligence project that tapped the very highest level of encrypted communications of the German armed forces, as well as those of the Italian and Japanese armed forces, and thus contributed to the Allied victory in World War II.

Source: “NCVA History Book” 1995 and “MacArthur’s Ultra” by Edward J. Drea 1992.