Before the Battle of Leyte Gulf occured, Filipino guerillas captured Admiral Shigeru Fukudome, chief of staff of Admiral Koga, who replaced Yamamoto.
Fukodome and Koga were traveling in seperate planes traveling from Palau to Davao when they were seperated due to a storm. Koga's plane was never found but Fukodome's Flying Boat was forced down in Cebu and he was captured by Filipino guerillas.
He was later released to prevent reprisals on Filipino civilians but all his papers were turned over to US authorities. Included in the papers were plans for the defense of the Philippines. According to columnist Bobit Avila of the Philippine Star, it was sent to Gen. Macarthur via the submarine USS Crevale.
According to his article, the captured plan influenced Macarthur to change his Philippine landing plan from General Santos City to Leyte.