Island Hopping - Chapter 12 of Radar and the Fighter Directors
By David L. Boslaugh, Capt USN, Retired
A New Strategy
In the conquest of the Marshall Islands, Admiral Nimitz decided to strike at the very center of Japanese defenses on Roi-Namur and Kwajalein Islands rather than the more heavily armed islands on their outer ring. These islands he simply cut off from their supply sources and let them wither on the vine without hazarding U.S. troops. The strategy worked well and would be used continuously throughout the rest of the Pacific War. The next step in moving U.S. forces closer to the Japanese homeland would be conquest of selected islands in the Mariana Islands group, specifically Saipan, Tinian, and Guam, while leaving major defended bases such as distant Rabaul alone. These would be isolated by submarine and air attacks on their maritime supply lines.
On 6 June 1944, Task Force 58, now numbering seven fleet carriers and eight light carriers under the command of Admiral Marc A. Mitscher, left its bases in the Marshall Islands and headed for the island of Saipan. The fifteen carriers carried 956 airplanes. Non-carrier strength of the force included seven battleships, eight heavy cruisers, thirteen light cruisers, and fifty-eight destroyers. RADM Clark’s Task Group (TG) 58.1 was in the lead, and on 10 June LT Ridgway’s CIC team detected Japanese patrol planes approaching the force. He vectored a CAP of covering Hellcats who brought down the first snooper at forty-seven miles and destroyed the second a few minutes later. Neither had a chance to send out a contact report. Later that day a land based navy Liberator bomber encountered a Mitsubishi G4M bomber that it proceeded to shoot down, but not before the “Betty” reported the task force’s position. The report was overheard by TG radio monitors, and as a result, RADM Clark requested permission of ADM Mitscher to send two picket destroyers fifty miles ahead of the task group, and one twenty-five miles ahead to act as communications relay. All destroyers had fighter director teams aboard and controlled their own CAP. On 11 June, long range Japanese patrol bombers attacked the task force, and the fighter directors aboard the picket destroyers and their CAP fighter pilots paid off handsomely by shooting down six patrol bombers forty miles away from the task force. [16, pp.158-160]
The Great Marianas Turkey Shoot
The American amphibious force began going ashore on Saipan on 15 June 1944, surprising the Japanese high command who had expected an invasion further south. But now they knew roughly where Task Force 58 was, and what they were up to. For Admiral Jisaburo Ozawa, this was the chance he had been looking for, the opportunity for his First Mobile Fleet to engage a major component of the U.S. Pacific fleet in a decisive sea battle. At the same time they would repel the Saipan invasion. The First Mobile Fleet had six heavy aircraft carriers, three light carriers, five battleships, thirteen heavy cruisers, six light cruisers, and twenty-seven destroyers plus 450 carrier airplanes, supported by 300 land based planes. On the seventeenth of June the First Mobile Fleet began steaming toward the Marianas from bases in the Philippines, and by the morning of the nineteenth were within air attack range of TF 58. At the same time, the Japanese launched land based attackers from Guam. At 0705 LT Ridgway’s radar operators on Hornet detected a large number of aircraft over Guam, and Ridgway vectored four fighters to see what was going on. They found a number of Japanese planes circling to land at Orote Field on Guam, and the Hellcats attacked, while informing Ridgway what they had found. He had twenty-four more fighters launched, while RADM Clark radioed the task force commander that they needed more fighters over Guam. The landing aircraft had pretty surely been dispatched from the approaching First Mobile Fleet. The Hellcats destroyed thirty-five Japanese planes in the air and on the ground at Orote, with the loss of one Hellcat. They might have scored even more, but at 0937 the task force FDO detected a large group of attackers coming from the west at 130 miles, and recalled the fighters from Guam to cover the force. ADM Mitscher gave the order to launch all torpedo and dive bombers and have them orbit safely east of Guam. This would free the carrier decks for fighter use, and get dangerous gasoline and bomb loads out of the way.
By 1000 450 Hellcats and a number of night fighter Corsairs had been launched to intercept the oncoming air armada. Under the coordination of Task Force 58 Fighter Director Officer LT Joseph R. Eggert, a former New York stockbroker, the fighter direction teams coached the fighters to favorable intercept positions at 25,000 feet. The Hellcats and Corsairs went through the oncoming formations in waves. The new Japanese pilots tried hard but did not have the experience or skill of the defending U.S. Navy pilots, who described the flaming and smoking Japanese planes as falling like leaves. Some attackers made it through the fighter screen, but most were brought down by massed AA fire, many projectiles being tipped with the new radar proximity fuse. Damage to ships was limited to a non-disabling bomb hit on the battleship South Dakota and minor damage to the carriers Wasp and Bunker Hill. In the mean time, 385 Japanese planes had been destroyed at a cost of forty Hellcats. [16, pp.165-170] [15, pp.100-104]
Two days later, on 21 June, Task Force 58 dive bombers and torpedo bombers finished the job on Admiral Ozawa’s First Mobile Fleet. In a dusk attack they sank the carrier Hiyo and two refueling tankers, and they badly damaged the carriers Zuikaku and Chiyoda, the battleship Haruna, and a heavy cruiser. The First Mobile Fleet was left with only 30 aircraft as compared to 450 two days earlier. [15, pp.105-107]
The Battle of the Philippine Sea during 19 and 20 June 1944 was the largest carrier versus carrier battle ever, and the last. It was a set piece example of what fighter direction should be. The Japanese raids came in at high altitude, with minimal evasive maneuvers, but from many points of the compass. Of the fighter direction during the attacks, Commander Task Force 58 noted:
The four major attacks were each hit at ranges of some 50-60 miles from the carriers and each time with sufficient altitude advantage to our fighters. It was the first time that a major enemy air blow has been made on our forces without the loss of or serious damage to at least one of our carriers. It proved that the long and costly efforts in research, training, and the practical application of radar have not been in vain.
...Every effort was made to insure that an adequate number of fighters were being vectored out against each raid....
..Insofar as possible every effort was made to insure that an adequate supply of fresh fighters was available for subsequent raids....
Of 33 interceptions initiated as a result of radar or visual contact, 28 were completed successfully, resulting in the destruction of 141 enemy planes. One of the most important factors in the success of fighter direction during this phase was the instantaneous reinforcement of standing combat air patrols. Whenever one division of the standing two division combat air patrol was committed to an interception, eight more fighters were immediately launched if another bogey contact appeared.
CTF 58 also observed that both radar and radio equipment were much improved over what was available in the 1942 and 1943 sea battles. Furthermore, not only were more fighters available because of the many new and larger carriers, but also the new Hellcat fighters were a considerable improvement over the Wildcats; showing that in most respects they were superior to the Zeros. The concept of carriers having nothing but fighters was brought in to play with Wasp and Hornet having ninety-one fighters between them. [13, p.39]
The abundance of fighters allowed their use in two ways during the battle. Not only could a task force keep a large, and constantly replenished, CAP overhead, but could also send many fighters to cover the enemy airfields on Guam where Japanese carrier planes were landing to refuel and rearm so they could re-attack without returning to their carriers. Thirty-five enemy planes were destroyed in these sweeps, thereby lightening the shipboard FDOs’ tasks. Also, the night before the battle, night fighters had been stationed above Japanese airfields throughout the Marianas to intrude on any attempted night harassing raids. Furthermore, day fighters swept the fields before the Saipan landing. Another contribution to this stunning victory was a shortage of seasoned Japanese pilots caused by aircrew losses at Midway and attrition during the Solomons Campaign. This was exacerbated by the Imperial Japanese Navy policy of not rotating experienced pilots out of battle. Japanese naval pilots stayed in combat until they were either killed or so severely wounded they could no longer stay in combat. On the other hand, American pilots were rotated home after about a year of combat so they could form and train new squadrons or serve as flight instructors. Either way, they could impart their combat experience to their juniors. Saipan was in Allied hands by July 1944, and Tinian and Guam in August. Airfield construction was begun immediately on Tinian and Saipan to host B-29 bombers to begin raids on the Japanese homeland. [13, p.39] [30, p.67] [15, p.99] [19, p.16] [58]
In August 1944, Admiral Nimitz performed an unusual rotation of senior commanders in the Pacific that almost caused RADM Clark to lose LT Charlie Ridgway, his TG 58.1 Fighter Director Officer. The Commander Fifth Fleet, VADM Raymond Spruance was to be replaced by VADM William Halsey, and Commander Task Force 58, VADM Marc Mitscher, was to be replaced by VADM John S. McCain. This was done to give the two incumbents and their staffs a well deserved rest, and to give Nimitz the benefit of their experience in planning forthcoming operations. Simultaneously with the command change, 5th Fleet became 3rd Fleet and Task Force 58 became Task Force 38, although there was no change in the ships involved. Part of the reason for the number change was to confuse the Japanese into thinking Pacific Fleet had more resources than it really had.
VADM McCain went aboard his flagship, the carrier Wasp, and in subsequent sorties, enemy aircraft occasionally strafed both Wasp and RADM Clark’s flagship, Hornet. When McCain asked Clark what could be done to stop the strafing, Clark replied he should get a good task force fighter director. McCain inquired how he could get one, and Clark made the mistake of mentioning his LT Ridgway as an example. That night Clark picked up a message from VADM McCain to Commander Naval Air Forces, Pacific (COMNAVAIRPAC) requesting Ridgway be permanently assigned to his staff. Fortunately the request was processed by Clark’s former executive officer now on COMNAVAIRPAC’s staff; who on the spot, invented a new qualification required for Ridgway’s career progression. He needed training at the Night Fighter Direction School, as NAS St. Simons Island near Brunswick, Georgia. Ridgway soon had orders to the school, after which he would return to RADM Clark’s staff. [16, pp.194-195]
Visual Fighter Direction
Fighter direction before radar was based on visual information, and even after the advent of radar there were certain conditions where visual air control could be the most appropriate method of fighter direction, these included:
- Locations where land echoes saturate radar.
- Close-in enemy planes below radar cover.
- Enemy aircraft at less than radar minimum range.
- Radars incapacitated by enemy jamming or other countermeasures.
- Failed radars.
- So many friendly planes close-in that visual recognition is called for.
[52, pp.153-155]
Visual fighter direction did not become important, and was hardly covered in FDO schools, until the summer of 1944 when the Japanese intensified low level daylight torpedo attacks. Even though by this time most carriers had SM or SP height finding radars that could detect low fliers, the height finders had to be coached on to targets by air search radars because of their narrow beams. On their own the height finders were not very adept at early detection of low fliers. The best way of detecting low flying attackers was still visual, and if detected, there had to be immediate communication with nearby CAP. Communication from lookout to CIC, and then CIC to CAP was too slow. The best way during daylight hours was permanent stationing of visual FDOs who could radio immediate orders and give the required rapid heading changes to line fighters up on the attacker. In recognition of this change in tactics, the Chief of Naval Operations issued a change to USF 10A, Current Tactical Orders and Doctrine U.S. Fleet, directing that fighter direction ships station a visual FDO in a high outside location.
Major combatant ships of the day were equipped with locations high in the superstructure, called “Sky” that served for visual air control. The Skys were equipped with gyrocompass repeaters, pelorus rings, plotting tables, phone circuits to lookouts and ship control centers, and access to voice radio circuits. They were usually manned by the most junior FDOs and had one or two enlisted plotters/radio talkers as assistants. This team was to receive all ship’s lookout reports, keep a sharp lookout themselves, keep a constant plot of all visible aircraft, keep CIC informed of new visual sightings, and be ready to assume control of nearby CAP. In September 1944 the Office of the CNO issued an updated fighter director vocabulary having a special section with a visual FD vocabulary. It was even more terse than the standard vocabulary, with shortened phrases to support the quick reactions needed. To begin with, the ship’s call sign was followed by the word “Snap.” For example, “this is Ganymede Snap.” This way, the pilots knew they were talking to a visual controller and should use the visual control vocabulary. Some examples of the vocabulary:
- Vector Pronto - Dive as low as possible and go on the magnetic bearing given.
- Steady - given after the controller has called for a port or starboard turn to tell the pilot to stop the turn. This works because the controller could see the aircraft’s heading.
- Up _ _ - Climb the number of feet given
- Masthead - Fly just above the water.
[52, pp.153-155] [13, pp.36-37]
The Battle of Leyte Gulf
General MacArthur’s original plan for gaining a beachhead in the Philippines called for a late October 1944 landing on the southern coast of Mindanao, the southernmost island of the Philippines, at Sarangani Bay where he could have an airfield site. In preparation for the invasion Task Force 38 aircraft raided a number of Japanese bases in the islands, and in the process of one of the raids on 11 September, Ensign Thomas C. Tillar, a Hornet aviator, was shot down near the central island of Leyte. He was rescued and returned to Hornet where he told RADM Clark that the natives who picked him up recommended Leyte as an invasion site because there were no Japanese there. Clark sent the recommendation up the chain of command, and in less than forty-eight hours a response came back that the proposal had been accepted, and the Leyte landing was scheduled for 20 October. [19, p.23] [16, pp.194-195]
Japanese Imperial General Headquarters had not given up yet, they still pinned their victory hopes on coming to grips with the U.S. Pacific fleet in one last decisive sea battle. Japanese naval air had lost most of its aircraft and aircrews, so the role of their carriers would be as decoy to entice a large part of the U.S. surface forces supporting the next invasion to chase the carriers while Japanese forces annihilated the invasion fleet with overwhelming land based air strikes and naval gunfire. The Japanese were sure there would be another major Allied landing soon, they just didn’t know where, and they had to be ready to move. Admiral Soemu Toyoda’s Combined Fleet had four major combat units ready:
- The 1st Striking Force composed of five battleships, ten heavy cruisers, two light cruisers, and fifteen destroyers based near Singapore.
- The 2nd Striking Force of two heavy cruisers, one light cruiser, and four destroyers based at Mako on the main island of Japan.
- The Northern (decoy) Force of one fleet carrier, three light carriers, two WW I battleships, three light cruisers, and nine destroyers located in the Inland Sea of Japan. The force had only 108 aircraft.
- Land based Navy air units at bases throughout the Philippines having approximately 300 airplanes.
[15, pp.113-114] [55]
The U.S. Naval order of battle for the invasion consisted of Vice Admiral Halsey’s Task Force 38 having more than 1000 aircraft, and Vice Admiral Thomas Kinkaid’s 7th Fleet. The 7th Fleet’s primary task would be transporting the invasion force and its supplies, with secondary task of shore bombardment, plus air cover by its light carriers. In addition to troop ships, cargo transports, and more than 400 amphibious ships, the 7th fleet would have six battleships, eight cruisers, a large number of destroyers, and eighteen escort carriers carrying approximately 500 aircraft to provide close air support. Task Force 38 with its eight fleet carriers and eight light carriers would be responsible primarily for invasion air cover with a secondary task of shore bombardment by its six battleships, fifteen cruisers, and forty-eight destroyers.
U.S. Army Rangers captured small islands on the approaches to Leyte on 17 October, and U.S. radio traffic intercepted by Japanese listening posts assured the Japanese that the next invasion was imminent there. The next day the forces of the Japanese Combined Fleet began their convergence on the island. The first striking force would split in two and come up from the southwest through the San Bernardino and Surigao Straits. They planned to close on the invasion force on the 25th when the invasion would be in full swing. The 2nd Striking force coming from the north would also circle back up through the Surigao Strait to join a couple of days later. Simultaneously, Admiral Ozawa’s decoy carrier force departed southward from the Inland Sea. [8, p.17] [19, pp.56-59]
On 17 October Vice Admiral Takajiro Ohnishi arrived in the Philippines to take command of the First Air Fleet, comprising all the land based aircraft on the islands. He soon learned that among his three air groups he had only 100 flyable aircraft; this was less than the number of ships in the Allied invasion fleet. Ohnishi realized that if his pilots were to be able to do any significant damage to such a huge force, each plane was going to have to destroy one ship, and the only way to do that was to deliberately crash a bomb-laden plane into each major ship. VADM Ohnishi visited the 201st Air Group at Mabalacat, Central Luzon, on 19 October and laid his ideas before the group’s officers. They agreed to form a “special attack group” of volunteer pilots, and when the air group commander asked for volunteers among his twenty-three petty officer pilots, all volunteered. On 20 October the Shimpu Attack Unit was formed around the twenty-three young pilots equipped with twenty-six Mitsubishi Zero fighters that had been modified to carry a 550-pound bomb. They named their unit Kamikaze, meaning “divine wind,” and the unit had orders to begin operations on 25 October. Thus was begun the Navy Special Attack Corps, and the idea would continue to blossom to the point that by war’s end in August 1955, five thousand Kamikaze pilots were being trained, and of the ten thousand remaining Japanese Army and Navy airplanes, half were assigned to special attack squadrons. [8, p.18, p.37, p.78]
From the twenty-first to the twenty-third of October, inclement weather prevented the Japanese from making more than sporadic air attacks on the invasion force, but did provide cover for bringing in 300 more aircraft of the Second Air Fleet from Formosa. On the morning of 24 October 1944 RADM Frederick C. Sherman’s Task Group 38.3 was ninety miles at sea directly east of Manila; their job to intercept any Manila area based aerial attackers that might try to disrupt the Leyte invasion. At 0807 the air search radar operators on the Task Group flagship Essex detected a large raid seventy-five miles to the west. They were stacked in altitudes from 1,000 feet up to 25,000 feet. Their order of battle was: fifty-four Zeros and twenty-eight torpedo bombers of the Air Mastery Squadron; six bomb-carrying Zeros of the 1st Attack Squadron; ten Zeros of the No. 2 Special Attack Squadron; fifty-one Zeros of the No. 3 Protective Squadron; and thirty-eight dive bombers of the No. 3 Bombardment Squadron. A total of187 aircraft. [8, p.19] [30, p.174]
Aboard Essex, Task Group 38.3 Fighter Director Officer LTJG John B. Connally looked over the status boards that showed the fighter and deck conditions of the two task group fleet carriers, Essex and Lexington, and the two light carriers Langley and Princeton. Connally had gone through the Fighter Direction School at NAS, St. Simons Island, Georgia, and was then posted to Essex as an assistant FDO. He was soon senior fighter director, and when RADM Sherman broke his flag in Essex, he became task group FDO. Noting the unusually large size of the raid showing on the radar screens, Connally had all fighters on missions return to the task group area with the distress signal “Hey Rube”. This was the only time as a task group FDO that he ever sent such a distress call. Next, he had all carriers launch every available fighter and then assigned specific fighter groups and targets to FDOs throughout the task group. [30, p.xi] [45, pp.43-44]
Soon, seven Essex Hellcats, led by Air Group Commander CDR David McCampbell were ready for launch. Connally, as task group FDO, did not normally conduct intercepts on his own, but rather coordinated the actions of other FDOs. He checked the assignments on his plots and saw that every FDO in the group was already very busy. So he personally took charge of vectoring two of them, McCampbell and wingman LTJG Roy Rushing, toward Zeros at 25,000 feet who were providing top cover for the oncoming enemy dive and torpedo bombers. When CDR McCampbell tallyhoed, he reported they were outnumbered about thirty-to-one, and asked for more fighters. Connally remembers listening to McCampbell tell his wingman which Zero to take on first and which one he was attacking. The dogfight lasted for over ninety minutes, and the two pilots broke off only when their ammunition was gone. Rushing had shot down six Zeros, and McCampbell, nine. All but one of the entire Japanese air armada had been either shot down or turned back. That one dive bomber, however, managed to conceal itself in the clouds directly above the task group where it could not be detected by radar, and when the protecting Hellcats moved off, it dove from cover and managed to put a 550-pound bomb through the flight deck of the light carrier Princeton. Among other damage, the bomb ignited fires in the carrier’s torpedo storeroom which caused torpedo warheads to explode. Princeton continued burning and exploding throughout the day until she had to be abandoned in the afternoon, and a torpedo from the light cruiser Reno sent her to the bottom. For his work that day, Connally was awarded the Bronze Star. [30, p.176] [45, pp.43-44] [18, pp.46-47]
On the morning of 24 October 1944 a Japanese Army bomber tried to crash into an assault transport off Leyte, but missed, hitting the fleet tug Sonoma instead. Her crew tried to beach her but the tug sank before they could make the shore, making her the first victim of a presumed Japanese suicide attack. Then on the 25th, the 7th fleet invasion force got its first taste of the Kamikazes when five special attack Zeros armed with 550-lb bombs escorted by three Zero fighters set out seeking targets of opportunity in the open ocean some forty miles southwest of the invasion area. Here they found sixteen small escort carriers of the 7th Fleet in the process of recovering aircraft. The small carriers and accompanying destroyers had just been in a furious battle with four battleships, eight cruisers, and eleven destroyers of VADM Takeo Kutita’s 1st Striking Force that had emerged from San Bernardino Strait. For some miraculous reason just about the time that Kurita’s heavies had the opportunity to finish off the small fleet of “jeep” carriers and destroyers, the Japanese broke off the action and turned away. The fighter direction teams in the American flotilla were busy recovering aircraft, had many friendly aircraft cluttering the skies around them, and did not detect the approaching special attack unit.
At 0740 one of the bomb laden Zeros crashed into the light carrier Santee’s flight deck, and the bomb exploded in the hangar deck, starting fires. In less than a minute, another Kamikaze went into the water just short of the escort carrier Petrof Bay, and the small carrier Sangamon suffered a near miss by the bomb from another special attack plane that crashed into the ocean nearby. Sixteen men were killed on Santee, but after eleven minutes her damage control teams had the fires damped down. At 0800 another special attacker made a hit in the middle of the light carrier Suwanee’s flight deck, causing severe personnel casualties, however, the flight deck was repaired in two hours. At 1051 the fifth special attack Zero penetrated into the escort carrier St. Lo’s hangar deck causing ammunition magazines to explode, and forcing abandonment. The ship sank thirty minutes after impact, to be the first major combatant ship to succumb to the Kamikazes. After seeing five Japanese aircraft crashing in sequence into American aircraft carriers, there was no doubt that they had initiated a new brand of aerial warfare. [15, p.119, p.123]
Bombers and torpedo planes had to operate together in large numbers if they hoped to inflict significant damage, but if a single suicuider could make a square hit, he almost always caused severe damage. Furthermore, the Kamikazes did not need to be coordinated, could come in at different altitudes and directions, and could maneuver violently to evade fighters and gunfire. This required defenders to send out increased numbers of CAP to intercept the separately attacking Kamikazes, and placed a much greater load on fighter directors at a time when they had to be even more effective. It was no longer enough to break up and disperse a raiding group, or to bring down most of a group, now the FDOs had to bring down every separate attacker. The challenge was made even worse on 28 October when a special attacker managed to sneak in and damage the light cruiser Denver while pretending to be part of a returning air strike. [13, p.39]
The planned pincer movement of the Japanese 1st and 2nd Striking Forces never closed on the Leyte invasion force. As mentioned above, the battleships and cruisers of ADM Kurita’s northern part of 1st Striking Force had inexplicably turned back while engaging the light carriers and destroyers of a small 7th Fleet task unit. The reason Kurita later gave was that he thought he was about to run into the main body of Admiral Halsey's Task Force 38. Meanwhile, the southern unit of the 1st striking force, under VADM Shoji Nishimura, that was to come up Surigao Strait had been literally blown out of the water on the night of 24-25 October by a force of American battleships. Then when VADM Kiyohide Shima, who was bringing the 2nd Striking Force up Surigao Strait saw the remnants of Nishimura’s ships, he decided it prudent to turn back. What ADM Kurita did not know was VADM Halsey had taken the bait of the northern decoy force of four Japanese aircraft carriers and escorts and had steamed north where he sank the fleet carrier Zuikaku, the light carriers Chitose and Zuiho, and the destroyer Akizuki. [8, pp. 19-24] [19, p.203] [14, p.123]
