Station HYPO

A great example how radio intelligence provided I&W ISO operation “OBLITERATION,”  – the invitation of Luzon, Philippines December 10-23, 1943.  Of note, the first kamikaze attack of the war began during the Battle of the Leyte Gulf, October 25, 1944.

Radio Intelligence Operators:

• CDR Gilven M. Slonim deployed on the USS New Jersey (COM3RDFLEET).  He received his language training in Japan 1939-1941 and retired in 1965 as a Captain.
• LT Ernest B. (Ernie) Beath deployed on the USS Handcock (COMTASKFOR 38).  He received his language training at Berkeley/Boulder, class 1942
• LTjg R. A. Wilson deployed on the USS Essex (COMTASKGRP 38.3).  It is unknown where he received his language training.

Background

The Philippines were considered to be of great strategic importance because their capture by Japan would pose a significant threat to the U.S. As a result, 135,000 troops and 227 aircraft were stationed in the Philippines by October 1941. However, LUZON —the largest island in the Philippines—was captured by Imperial Japanese forces in 1942 during their campaign to capture the Philippines. General Douglas MacArthur—who was in charge of the defense of the Philippines at the time—was ordered to Australia, and the remaining U.S. forces retreated to the Bataan Peninsula.

A few months after this, MacArthur expressed his belief that an attempt to recapture the Philippines was necessary. The U.S. Pacific Commander Admiral Chester Nimitz and Chief of Naval Operations Admiral Ernest King both opposed this idea, arguing that it must wait until victory was certain. MacArthur had to wait two years for his wish; it was 1944 before a campaign to recapture the Philippines was launched. The island of LEYTE was the first objective of the campaign, which was captured by the end of December 1944. This was followed by the attack on MINDORO, and later, LUZON.

Mobile Radio Intelligence Support (verbatim):

“The objective in the December operation was the further reduction of the Japanese Air Force on LUZON ISLAND in preparation for later landings, and support of scheduled landings on MINDORO ISLAND.

Task Force 38 sortied from ULIGHI Atoll on 10 December.  On the 11^th the force conducted firing exercise enroute to the launching position.  Radio intercepts indicated continuing enemy reconnaissance of LEYTE GULF.  Several grid type contacts were noted on 5135J (A), all of which broke to positions in the LEYTE GULF area.

12 December produced no intercepts pertaining to Task Force 38.  At 0633 an enemy plane on 5135J reported that he had sighted seven “enemy” destroyers bearing 180 degrees from ORMOC BAY, distance eighteen miles, course 180 degrees.  In the attack which followed this contact one Blue (B) destroyer was sunk.  All air activity for the day centered in the LEYTE GULF area, with grid contacts in that area appearing throughout the day on 5135J.

On 13 December the force refueled preparatory to the run-in to the launching position during the afternoon and evening. At 1215 a plane on 5135J sent a message indicating successful reconnaissance of an unidentified area, specifying that sixty-five ships were present.  The contact was evaluated as on the anchorage in LEYTE GULF.  Interception produced no evidence of an attack resulting from this reconnaissance report.  Several grid contacts were copied on a secondary channel, but the unlikely positions given made it appear to be probable communications drill.

The task force struck LUZON based on the morning of the 14^th.  A series of messages were received from a plane on 5135J.

• 1221 – “My bomb won’t release.  Am heading for LEYTE GULF for body crash.”
• 1226 – “Am over LEYTE ISLAND.”
• 1231 – “Am over BOHOL ISLAND.”
• 1233 – “There is no enemy fighter opposition.”
• 1239 – “Am attackin”
• 1246 – “BANZIE.”

At 1315 the DD SHIOKAZE (C) reported contact with Blue planes in position 119-43E 16-00N. This information was forwarded to the commands and during the next strike Blue planes were ordered to that area to attack this ship.  No enemy air contacts with the task force were noted during the 14^th.

The assault on LUZON objective was continued on the 15^th, and landings on MINDORO ISLAND were accomplished during that day.  Continuing attack on the MINDORO invasion force were noted on 5135J.  An evening attack was watched on this channel.  At 1852 “have reached target” was copied.  At 1900 the same plane reported “attacks completed.  Hit one transport.” At 1905 this plane completed his transmission with a report of the weather in target area.

16 December brought a continuation of the carrier assault.  At 0305 the force was contacted for the first time during this operation.  The snooper penetrated close to the force and showed on the radar screen.  At 0420, despite night fighter efforts to intercept, two grids on carrier groups of the force were transmitted.  About 0800 the Force CAP shot down eleven enemy planes intercepted while enroute to the Task Force.  No additional contacts with the carrier force were heard, although Blue forces in LEYTE GULF and at MINDORO ISLAND were under bombing  and suicide attacks on 5135J throughout the day and night.

On 17 December the Task Force withdrew from the launching position to refuel.  Intercepts on 5135J indicated that enemy efforts against LEYTE and MINDORO were continuing.

The Force refueled on 19 December well away from its normal fueling position.  Enemy air activity was very light during the day.  At 1845 an enemy disposition report for an unindicated area was copied.  A follow-up weather report was heard at 1848.  At 1859 was reported “bombing completed – three hits.”

On 20 December the Force began its run to the launching position off LUZON.  Enemy air activity was negligible until 1700, when planes came up on 5135J.  Grids at 1900 and 1922 indicated that searches were being conducted in the LEYTE area.

On 21 December the force attempted to resume the carrier assault on LUZON objectives but was unable to do so due to heavy weather. The strike was cancelled and the force proceeded to the fueling area preparatory to returning to ULITHI Atoll.  About 0300 a single bogie using 5135J for communications showed on the radar screen.  He sent a grid type report of the position of TF38 (D) shortly after 0400.  Two more search planes were sent into the area later in the morning but failed to make contact.  Although the carrier force was not attacked, heavy activity on 5135J with grid contacts during the night indicated that Blue forces in LEYTE GULF and at or near MINDORO ISLAND were thoroughly reconnoitered and probably attacked.

As the Task Force retired on 22 December, radio interception indicated that one enemy plane was on search well to the east of LUZON. Grid contacts intercepted suggested that he made contact with Blue units searching for survivors of disasters during typhoon of the 18^th (E).

23 December found the forces retiring to ULIGHI Atoll.

Shortly after midnight several squadrons of enemy planes came up on 5135J.  No traffic was received from the planes and the objectives of the missions could not be ascertained.  Nothing of import to TF38 was heard during the day.

On 24 December the Task Force arrived at ULITHI Atoll to replenish and prepare to support the U.S. occupation of LUZON.”

Footnotes:

• (A) 5135J is probably a reference to a Japanese Navy Air communications network, frequency in HF or channel.
• (B) Blue is a reference to U.S. or Allied Forces.
• (C) Minekaze-class Japanese destroyer
• (D) USS Handcock
• (E) Typhoon Cobra, also known as Halsey’s Typhoon, was the United States Navy designation for a powerful tropical cyclone that struck the United States Pacific Fleet in December 1944, during World War II.

Source: Command Display, Corry Station

Featured Image: The battleships Pennsylvania and Colorado lead three heavy cruisers into the Lingayen Gulf for the pre-assault bombardment of Japanese shore positions.