© 2006-2009 Bob Hackett and Sander
Midget Submarines in the Marianas
17-18 February 1944: American Operation
"Hailstone" - The Attack on Truk:
Caroline Islands. Vice Admiral
(later Admiral) Marc A. Mitscher’s Task Force 58's five fleet carriers and four
light carriers, supported by six battleships, ten cruisers and 28 destroyers,
launch air attacks on airfields, shore installations and ships in the lagoon.
Mitscher launches 30 strikes of at least 150 aircraft each. Beginning at dawn,
strikes are launched about every hour for two days.
During the raids, TF 58 sinks 31 merchant transports and 10 naval vessels
(two light cruisers, four destroyers and four auxiliary vessels, destroys nearly
200 aircraft and damages severely about 100 more. Truk is eliminated as a major
fleet anchorage for the IJN.
Truk Atoll, Caroline Islands
After the attack on Truk, the IJN decides to establish
a midget submarine base on Eten (Takeshima) Island, Truk as protection against
any pending American landing. In the event, no midget submarines are ever
stationed at Truk, but their technical crews, cranes and other equipment are
delivered there by various unidentifed ships.
20 February 1944:
Five Type C midget
submarines are transferred from Ourazaki (Base P) at Kurahashi Jima to Yokosuka
and depart for Truk in two batches.
Detachment "A" (Ko) consisting of three midget submarines
under Lt ( j.g.) Sato Masayoshi is transported to Truk via Guam by unidentified
ships at an unknown time. In May, they arrive at Saipan.
(U.S. Marine Corps)
19 May 1944:
Detachment "B" (Otsu) consisting of two midget submarines
under Lt ( j.g.) Fukasa Yasuzo departs Yokosuka for Saipan towed by HORAISAN and
SHOKEN MARUs in convoy No. 5319 (or 3519) escorted by kaibokan CD-16.
29 May 1944:
Marianas. Early in the morning, the convoy is spotted by
lookouts aboard LtCdr (later Rear Admiral) John S. Coye's USS SILVERSIDES
(SS-236). Coye fires three bow torpedoes at each ship and sinks both HORAISAN
and SHOKEN MARUs. Both of Lt ( j.g.) Fukasa's Detachment B's two midget
submarines, twelve Type 97 torpedoes and three crewmen are lost.
12 June 1944: American Operation “Forager” – The Invasion of Saipan,
Vice Admiral (later Admiral) Richmond K. Turner’s Task Force 52
lands Marine LtGen Holland M. Smith’s V Amphibious Corps and the invasion of
Saipan begins. Communications between Vice Admiral (Admiral, posthumously)
Takagi Takeo’s (former CO of MUTSU), Advance Expeditionary Force (Sixth Fleet)
are disrupted by the invasion. Command of the Sixth Fleet’s submarines passes to
Rear Admiral Owada Noboru (former CO of YAMASHIRO), ComSubRon 7 at Truk.
ENTERPRISE (CV-6) off Saipan
(Naval Historical Center)
12 June - 8 July 1944:
Saipan, Marianas. After the American landing,
the crews of Lt ( j.g.) Sato's Detachment A's three midget submarines destroy
their vessels and join the Sixth Fleet's staff. Later, they die to the last man,
probably fighting as infantrymen.
Guam, Marianas. A Type "C" midget
submarine is discovered in shallow waters off Togcha beach near Talofofo, Guam.
The two crew members surrender three days later. 
Guam. The crew of Captain J. P. Thew's submarine
tender USS SPERRY (AS-12) constructs a rest camp on Guam for submariners and
support personnel. The area is named "Camp Dealey" in honor of Cdr (MOH,
posthumously) Samuel D. Dealey, CO of USS HARDER (SS-257), KIA in Aug '44 with
his 78-man crew.
Guam. The midget submarine discovered in Aug '44 is placed on
display at Camp Dealey. 
HA-51 at Guam in 1945
(U.S. Naval Historical Center)
The submarine is moved to U.S. Naval Base Guam.
Midget submarine “HA-51” is listed in the National
1 October 2001 - 30 September 2002:
During FY02, HA-51 is completely
restored for COMNAVMARIANAS under a $247,000 contract. This is likely the last
Type C midget submarine in existence.
1 April 2008:
The U.S. Naval Forces Marianas transfers possession of HA-51 to the National Park Service's T. Stell Newman Visitor’s Center outside the main gate of U.S. Naval Base Guam.
 This may be one of Lt ( j.g.) Fukasa's Detachment B's two midget
submarines. When its towing vessel sank, the craft probably broke loose and
started to drift.
 The number "51" was painted on the midget submarine's conning tower
indicating that it may be HA-51; however, some Japanese sources doubt this
identification. The hull was severed behind the conning tower with a short gap
between the forward and after sections.
-Bob Hackett and Sander Kingsepp
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