CVE-63 was laid down on January 3rd, 1943 as the USS Chapin Bay, the ninth of the Casablanca class of escort carriers. These were light ships, displacing about 10,900 tons fully loaded and built off of modified merchant ship hulls, intended for submarine hunting, ground support, and aircraft transport from the US to the various fronts of the war.
On April 3rd, 1943 her name was changed to Midway. On August 17th Midway was launched, and was commissioned into the US Navy on October 23rd, 1943. In late 1943 and into 1944 Midway ferried equipment from the West Coast to Pearl Harbor to Australia before joining Carrier Support Group 1 for the Marianas Campaign.
Midway was renamed to St. Lo on October 3rd, 1944 to free up the name 'Midway' for the next class of large fleet carriers. Starting on the 17th, St. Lo's aircraft provided support for Army Rangers and the landings at Tacloban on the island of Leyte, as well as striking targets on several other nearby islands.
On October 25th, 1944, elements of the Shimpu Tokubetsu Kogeki Tai, part of the 201st Air Group of the Imperial Japanese Navy, departed their base on Mabalacat towards the American fleet off the island of Leyte. Supporting the invasion of the island of Leyte were task units of small escort carriers, destroyers, and destroyer escorts. These forces were numbered as Task Units 77.4.1, .2, and .3, better known as Taffy One, Taffy Two, and Taffy Three.
Earlier that morning, these ships had come under attack by the Center Force of the Imperial Japanese Navy, a powerful collection of surface ships, including four battleships (Yamato, Nagato, Kongou, and Haruna), six heavy cruisers, two light cruisers, and eleven destroyers. During the battle, the Center Force withdrew after desperate attacks by the ships and aircraft of 77.4, ultimately losing three heavy cruisers and suffering damage to most of the ships in the force. The Americans lost a single escort carrier, two destroyers, and a destroyer escort in addition to damage to several other ships.
By 1010 the surface action was over, and St. Lo (CVE-63) had emerged undamaged from the battle. Her crew started to recover and rearm aircraft and the ship was secured from General Quarters.
At 1050, GQ was sounded again as aircraft approached, both allied and enemy. Anti-aircraft fire shot down several of the planes, but three of them focused on St. Lo. Two of them were knocked down by the American fire, but one of them came from astern, evading the AA fire.
Lt. Yukio Seki (photo above, probably taken just before his last flight) was at the controls of the A6M Zero that dove towards the flight deck, intent on using not only the 250 Kg bomb slung under the fuselage, but his own aircraft as a weapon against the fragile ship.
He released his bomb, but it's unclear if he actually managed to strike the ship with his A6M. But the results were catastrophic anyway. Secondary explosions from the ordinance in the hanger deck doomed the ship, and within 30 minutes, St. Lo had rolled over and sank with 126 of her crew.
The crew of R/V Petrel located the wreck of St. Lo on May 14th, 2019 and dived on the wreck on May 25th. They posted a video of their findings on the 10th of October to their Facebook page.
The Wreck
The extent of the damage can be seen even in the sonar images. St. Lo rests 15,540 feet below the surface of Leyte Gulf, just a bit more than 2.9 miles down. Helpfully, the general plans for USS Thetis Bay (CVE-90) are available on the internet, so sections of those plans will be posted to give more information on what can be seen of the wreck.
This is a high-frequency sonar pass of the wreck, which shows how extensive the damage from the explosions was. The bow is pointing to the upper right, the hole for the forward elevator can be seen clearly. The large piece of debris above the main part of the wreck is the end section of the flight deck, which detached as the ship sank.
Roughly the stern half of the ship has been devastated by explosions, consumed by fire, or was swept away as St Lo. sank.
These photos are of the stern, on the starboard side, including the starboard propeller shaft.
It looks like the bulk of the hull above the shaft has been destroyed, probably from the extensive secondary explosions that tore through the stern of the ship. Even the propeller shaft has been bent, similar damage can be seen on the port side as well.
Most of the hull that was above the waterline here looks to have been destroyed or otherwise lost.
According to the video, this is damage just aft of the island but there isn't enough footage or information given to pinpoint where this actually is. While it looks like bomb damage, this is probably more damage from munitions aboard St. Lo which exploded in the sinking.
This is the level of the hangar deck, again located aft of the island.
The ladder that can be seen towards the right side is the one just below the motor whaleboat, and the double hatches lead onto the floor of the hangar deck. It leads up to the upper deck, which is the level of the whaleboat.
To the far left are what are probably uptakes from the boilers, the funnel that they directed exhaust to can be seen in the diagram above between the two life floats just below the flight deck.
Here is the tub for one of St. Lo's 20mm cannons, on the level of the gallery deck, just above the hangar. There were 20 of these Oerlikon cannons around the perimeter of the flight deck, which were the last line of AA defense for the ship.
The cannon is missing from the tub, as are most of the AA weapons that were on the ship. The object on the left side looks to be a fuel pump, also on the general plans, there is a gasoline line that heads up towards the flight deck.
In the distance above the pedestal is an open hatch, which has a visible nameplate.
The island comes into view on the right side, and the open hatch can be seen more clearly on the left side, including the number for the compartment.
This number confirms the exact location on the wreck the video was taken of. At this moment I'd like to point out the different types of annotated hatches that can be seen. Some of them are a fairly typical 'door' style, like many of the ones around the RADAR rooms to the right of the shelter. But others are an hourglass shape which probably denotes another type of hatch that is more resistant to fire.
This is the observation platform/gunnery control platform on the island. This included the signal platform, the captain's battle station, and the flag plot which was the base for the mast.
Later in the video, the ROV made a pass over the flight deck towards the island from the port side, which showed the hatches into the captain's sea cabin and into the rest of the island.
These are the telegrams that indicate the speeds of the two propeller shafts in the captain's station.
Just below the flight deck and forward of the island is the winch platform and the aircraft handling boom, which can be seen laying across the shot right in the center.
Looking father towards the bow, more of the boom can be seen, as can one of the 20mm gun tubs.
A portion of the flight deck that broke or was blown off came to rest on the flight deck. More of the aircraft boom can be seen here as well.
On the right part of a director for some of St. Lo's 40mm Bofors guns can be faintly seen.
The director itself, or rather what's left of it. Just past it is were some extensive damage has occurred, including the loss of large sections of the flight deck.
This looks to be an inverted section of the flight deck, at least partially, based on the supports that can be seen on the tub to the left side.
The number on the hull confirmed the identity of the wreck, which also shows how deeply the hull dug into the seafloor.
Something interesting is how the paint has been scraped away from the bow by the swinging motion of the chain, that's something I don't recall seeing before on a shipwreck.
The ROV rounded the bow and made its way back down the port side of the ship.
The upper deck around the windlass is littered with debris, but it can't be clearly identified.
This is a paravane, a tool used to sweep for mines. When deployed by a moving ship, it would sink under the water, and the cable between it and the ship would catch the mooring cable of a mine. The paravane would be pulled against the cable, and the cutter (which can be seen clearly in the lower photo) could sever the mine cable. Now that it was unmoored, the mine would float to the surface where it could be destroyed by gunfire.
St. Lo had two of these on the upper deck, below the forward section of the flight deck. When the ship sank and the flight deck was torn away, it clearly did a lot of damage to the compartments below it. The compartments in this area were officer's quarters as can be seen on the drawing below.
I suspect that this is part of the catapult machinery, because that's the only apparent large machinery directly under the flight deck, and because of the apparent double doors that can be seen on the right side.
St. Lo had either Mark 2 or Mark 4 mounts for her Oerlikons, each of which weighed more than 1,600 pounds, 250 pounds of which were comprised of the half-inch thick steel shield. These were more effective than the .50 Browning machine guns they frequently replaced, but with the rise of suicide attacks their effectiveness waned as they did little to discourage a pilot who was intent on dying anyway.
The two open hatches behind the cannon are to a crew head (on the right) and to a clipping room (on the left). Clipping rooms were where the magazines and clips of the AA guns were loaded from loose ammunition, such as the 60 round magazine for the Oerlikon and the four-round clips for the Bofors guns.
Despite being half an inch thick, the shield is very badly bent.
The damage becomes far more severe closer to the stern, including this break in the hull.
This is probably another crew shelter, but with the damage and quality of the video, the number of the compartment is illegible.
At the end of the wreck, the port side propeller shaft is in a similar condition to the one on the starboard side. Most of the ship past this point is missing as well.
Each screw was 12.25 feet in diameter, and both are missing from the wreck. Probably in the debris field somewhere, but the depth makes a full survey complicated.
There don't seem to be any aircraft left on the carrier, several of which are known to have been lost on the hanger deck to the explosions from the stored ordinance.
Approaching the island from the port side reveals some fairly intact wood on the flight deck and one of the twin 40mm Bofors guns.
The observation platform was badly damaged, probably by the action of the sinking since the photographs of St. Lo before she sank show the island as being mostly intact.
The remains of the flag plot and mast base.
The navigator's sea cabin is to the left, towards the bow of the ship, and the captain's sea cabin is to the right. Unfortunately, I have not found any photos of the interior of the island on a Casablanca class escort carrier.
The 40mm Bofors gun was the main AA weapon on St. Lo, eight twin mounts were located at the ends of the ship, each served by a director. While she did have a single 5''/38 DP gun on the fantail, it had limited traverse though, and limited fire control facilities.
The two large tubs at the ends of the ship on each side are the 40mm mount locations, and the directors are slightly closer to amidships from the 40mm mounts.
It is odd that one of these weapons landed on the flight deck since none of them were located particularly close to the island. It just goes to show the extent of the damage that sent parts of the ship in all directions.
Another twin Bofors, partially buried in the silt. On the right side is a steel M1 helmet, worn by gun crews to protect from falling shrapnel. Sadly there is a large collection of plastic trash caught on the gun.
The forward part of the flight deck, looking at it from it's port side. This is a tub for one of the 40mm mounts, to the left is where the catapult controls would have been.
The pattern on the front can be matched with the pattern seen in photographs of the ship, which firmly identifies what part of the ship this is.
On the starboard side is another 40mm gun tub.
The depth of the wreck limited the ability of the ROV to survey the debris field, and at the time of this writing, no further information has been released.
Sources:
https://www.facebook.com/rvpetrel/ - Offical Facebook page for the R/V Petrel.
http://ussstlo.com/ - Offical website of the ship and her survivors.
http://www.navsource.org/archives/03/063.htm - Photographs of the USS St. Lo.
http://www.shipcamouflage.com/usn_cve.htm - Camouflage Measures for Casablanca class carriers.
https://ww2db.com/other.php?other_id=18 - Tokko "Kamikaze" Special Attack Doctrine.
https://ww2db.com/person_bio.php?person_id=297 - Biography of Yukio Seki.
https://www.history.navy.mil/research/histories/ship-histories/danfs/m/midway-ii.html - General history of the ship.
https://maritime.org/doc/plans/index.htm - General plans for warships.
https://maritime.org/doc/guncat/index.htm - Catalog of American WWII shipborne weapons.
http://www.navweaps.com/Weapons/WNUS_2cm-70_mk234.php - Detail information on the 20mm Oerlikon cannon.
http://www.navweaps.com/Weapons/WNUS_4cm-56_mk12.php - Detail information on the 40mm Bofors cannon.
Interesting facts about the mine cutter.
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