Battle of the Philippine Sea

Order of Battle:

United States
(TF 58) VADM Mitscher:
7 carriers
8 light carriers
7 battleships
67 destroyers

Japan
ADM Ozawa
5 carriers
4 light carriers
5 battleships
10 destroyers

VADM Ugaki
Yamato
Musashi
2 heavy cruisers
9 destroyer screen

VADM Kakuta
100 land based planes on Guam Island

Summary of Action
On the morning of 15 June, the morning of the Marines' assault on Saipan, reports came from the submarines Albacore and Seahorse that two separate Japanese battlegroups were steaming towards the Mariana Islands at full speed. Realizing that the two battle groups had to be part of a counter-assault on Saipan, Fifth Fleet Commander Vice Admiral Raymond A. Spruance postponed the landing on Guam and used the naval forces as a point defense for Saipan. The forces under VADM Mitscher would remain within a 200 nautical mile radius of Saipan so as to allow the aircraft to provide air support for the Marianas at all times.

The afternoon of 16 June, the Japanese force made rendezvous about 800 nautical miles from Saipan and refueled. They proceeded another 100 nm and then turned towards Guam on the morning of 17 June. At this point, the submarine Cavalla detected 15 of the ships from the combined Ozawa/Ugaki fleet. Spruance connected the missing ships to a Japanese tendancy to overengineer their plans and hypothesized that the detached force was a decoy to draw Mitscher away from Saipan allowing the heavier guns of the battleships to provide close naval gunfire to the Japanese troops still defending Saipan. Spruance responded by detaching RADM Lee's battleship group to serve as an AA screen and radar picket. Meanwhile, Mitscher was ordered to remain tethered to Saipan.

Ozawa, realizing that Mitscher's initiative was restrained, launched the first attack at 0830 on 19 June. It consisted of 53 bombers and torpedo planes with an escort of 16 fighters. At 0900, another, larger strike was launched. Mitscher, with information from his picket units had already launched his F6F Hellcat fighters to meet the strike. The convergence occurred at 1030 with all but 17 of the Japanese planes shot down in exchange for a single bomb hit on the battleship South Dakota. The one-sided shootout continued on the second wave when 70 planes were shot down by US carrier-based fighters and 27 were downed by AA fire. The Japanese earned one "bomb" hit when a torpedo-bomber crashed into the Indiana. The largely one-sided losses can be attributed to the relative inexperience of the Japanese pilots compared to the battle-hardened US pilots combined with poor logistical support for Ozawa's fleet. Ozawa launched another 47 plane raid at 1300 and a final 82 plane raid at 1400. Neither of these successfully engaged the US surface forces, although losses were sustained when patrolling escort aircraft attacked.

At this point, the US Submarines shifted from the surveillance role to the hunter/killer role. at 0900 on 19 June, Albacore snuck into Ozawa's battle group and placed a torpedo into the keel of his brand-new flagship the Taiho. At 1200, Cavalla sent three torpedos into the middle of the battle group and landed three hits on the Shokaku. Although Shokaku sank immediately, Taiho managed to flounder until the Shokaku explosion set off poorly refined, volatile oils in her hull, causing a huge internal explosion that split the ship in two sinking her almost immediately.

By nightfall on 19 June, Spruance was convinced that first, the Japanese were on the run, and second, they had been crippled to the point where a counter-strike was impossible. Releasing the tether on the task force, Mitscher ordered the battle group to 23 knots and a westerly course. Task Force 58 had been given a hunting licence. Searches at daybreak revealed no sign of the retreating Japanese fleet, but at 1540 on 20 June, airborne patrol craft from USS Enterprise found the retreating Japanese. They were reported at 275 nautical miles to the northwest (although modern historians believe the distance was closer to 350 nautical miles). Mitscher authorized an alpha strike of over 200 planes, which managed to sink the light carrier Hiyo, although no other major damage was inflicted.

At this point, the planes had to turn back, and Mitscher was faced with the decision of turning on the landing lights. Japanese submarines could home in on the landing lights, but without them the returning fighter-bombers would not make it back to the carrier. Mitscher decided to turn on the lights, thus saving all but about 80 planes. The battle ended without further incident. Although the battle had the effect of crippling the Imperial Japanese Navy's air abilities (as they had almost no trained pilots remaining at this point), Mitscher expressed regret that Spruance had not allowed him to join the pursuit earlier and thus perform a death blow upon the remaining fleet elements. Nonetheless, the Battle of the Phillipine Sea remains one of the most one-sided victories in all of carrier aviation warfare, and marks the last time the Imperial Japanese Navy effectively entered combat with air forces. The lack of air cover played a critical role in the events to follow in the battles of Leyte Gulf.