(Type J3 submarine - colorized photo by Irootoko Jr)

IJN Submarine I-7:
Tabular Record of Movement

© 2001-2017 Bob Hackett & Sander Kingsepp
Revision 9

12 September 1934:
Laid down at Kure Navy Yard.

3 July 1935:

3 July 1936:
Cdr (later Captain) Teraoka Masao (46)(former damage control officer of ERIMO) is appointed the Chief Equipping Officer (CEO).

31 March 1937:
Completed and attached to Yokosuka Naval District. Cdr Teraoka is the CO.

20 December 1937:
Cdr (later Captain) Fujimoto Tsutae (48)(former CO of I-73) is appointed the CO.

29 June 1938:
Cdr (Rear Admiral, posthumously) Iwagami Eiju (46) (former CO of I-56) is appointed the CO.

15 November 1938:
Cdr (Rear Admiral, posthumously) Okamoto Yoshisuke (47)(former CEO of I-75) is appointed the CO.

20 October 1939:
Cdr (Captain, posthumously) Ishikawa Nobuo (49) (former CO of I-3) is appointed the CO.

30 October 1940:
Cdr Nagai Komei (48)(former CO of I-6) is appointed the CO.

15 November 1940:
Assigned to SubRon 2, Sixth Fleet.

20 August 1941:
Cdr (later Captain) Koizumi Kiichi (49)(former CO of I-72) is appointed the CO.

21 October 1941:
Saeki Bay. Early in the morning, I-7 and I-66 collide during maneuvers, both receive minor damage.

10 November 1941: Operation "Z":
Saeki Bay. I-7 is in Vice Admiral Shimizu Mitsumi's (former CO of ISE) Sixth Fleet as the flagship of Rear Admiral (later Vice Admiral) Yamazaki Shigeaki's (former CO of old CA YAKUMO) SubRon 2. I-7 is in SubDiv 8 with I-4, I-5 and I-6.

Admiral Shimizu convenes a meeting of all his commanders aboard the Sixth Fleet's flagship, light cruiser KATORI. Cdr Koizumi and the other commanders are briefed on the planned attack on Pearl Harbor.

11 November 1941:
Reassigned to Captain Imaizumi Yoshijiro's Submarine Advance Force.

16 November 1941:
ComSubRon 2 Rear Admiral Yamazaki transfers his flag to I-7. The submarine also embarks a Watanabe E9W1 Type 96 "Slim" floatplane. At 1300 she departs Yokosuka for the Hawaiian Islands.

2 December 1941:
I-7 is located 300 miles N of Oahu when she receives the coded signal "Niitakayama nobore (Climb Mt. Niitaka) 1208" is received from the Combined Fleet. It signifies that hostilities will commence on 8 December (Japan time). [1]

7 December 1941: The Attack on Pearl Harbor:
Off Hawaii. SubRon 2 is arrayed to the northeast and northwest of Oahu. Its mission is to reconnoiter and attack any ships that try to sortie from Pearl Harbor. I-7 is the flagship for the subs stationed N of Oahu.

10 December 1941:
In the evening, Cdr Koizumi receives an order from flagship KATORI to conduct a recce flight over Pearl Harbor in order to assess the battle damage and survey the progress of repair works.

16 December 1941:
26 miles W of Kailua, Hawaii. Early in the morning, I-7 launches her Watanabe E9W1 "Slim" floatplane piloted by CPO Kaga Mitsunobu to conduct a flight over Pearl. At 0710, the observer, FPO2C Okamoto Murao reports four battleships (including three with cage masts and one heavily damaged) and an aircraft carrier off the East Loch anchorage. Okamoto also counts five cruisers and 30 smaller vessels including three destroyers S of Ford Island.

At 0945, the floatplane lands next to I-7. Both flyers abandon their plane and swim to the submarine. After scuttling the "Slim", I-7 dives and departs that area. [2]

17 December 1941:
I-7 is directed to a new area SW of Oahu to support SubRon 2's new sweep line formed in that area.

21 December 1941:
Detached, proceeds to the area SE of Oahu.

1 January 1942:
120 miles SE of Oahu. After nightfall, Cdr Koizumi sights a light cruiser and two destroyers heading for Pearl. He initiates a torpedo attack, but misses. In turn, the destroyers drop six depth charges, but fail to cause any damage.

9 January 1942:
Departs her patrol sector SE of Oahu, participates in the pursuit of a LEXINGTON-class carrier sighted by I-18 before heading for Kwajalein.

22 January 1942:
Arrives at Kwajalein.

24 January 1942:
Departs Kwajalein for Yokosuka.

2 February 1942:
Arrives at Yokosuka.

8 February 1942:
Reassigned to Vice Admiral Takahashi Ibo's Netherlands East Indies Invasion Force. I-7 is designated the flagship of Rear Admiral Ichioka Hisashi's Submarine Group "C" (Hei) with I-1 through I-6.

11 February 1942:
Departs Yokosuka for Staring Bay, SE Celebes (now Sulawesi).

16 February 1942:
Arrives at Palau, departs on the 17th for Staring Bay.

21 February 1942:
Arrives at Staring Bay, Celebes.

23 February 1942:
At 0600 (local), I-7 (with Rear Admiral Ichioka embarked) departs Staring Bay on her second patrol to intercept Allied ships attempting to escape from Java. After forming a sweep line 400 miles S of Java and interdicting Allied shipping heading for Australia, Group "C" is tasked with patrolling off Cocos Islands before advancing to Penang Island, Malaya. I-7 leads I-4, I-5 and I-6.

25 February 1942:
Indian Ocean, S of Sumba, Lesser Sunda Islands. Around noon, when running on the surface and displaying all prescribed recognition markings, I-5 and I-6 are attached by nine A6M2 "Zeke" fighters from the 3rd NAG's Ambon detachment. Misidentifying both subs as Dutch, the fighters repeatedly strafe them. I-5 receives serious damage and is forced to abort her patrol.

2 March 1942:
Indian Ocean, 150 miles SE of Cocos Islands. At 1230, I-7 is attacked by an unidentified IJN carrier plane, but receives no damage.

4 March 1942:
250 miles NW of Cocos Island. At 1000, I-7 battle-surfaces on the Dutch 865-ton motor vessel MERKUS independently en route from Tjilatjap to Colombo with a cargo of rubber. After the crew has left the ship, I-7 scuttles it with with her twin 140-mm deck gun at 08-40S, 94-30E. The entire crew of MERKUS later reaches Sumatra. [3]

9 March 1942:
At 0830, arrives at Penang.

28 March 1942: Operation "C":
Headquarters, Combined Fleet orders that the western coast of India and Ceylon be reconnoitered before the commencement of Operation "C". All of SubRon 2's boats, except I-1, are to participate in the operation. At 1600 (local), I-7 departs Penang on her third war patrol, carrying an E9W1 floatplane. She is tasked with conducting aerial reconnaissance of Colombo and Trincomalee two days prior to air attacks.

1 April 1942:
180 miles SE of Ceylon. At 0517 (local), the surfaced I-7 is attacked by an RAF PBY "Catalina" which near-misses her with two bombs. [4]

Four hours later I-7 encounters several small patrol vessels in the same area. Cdr Koizumi decides to cancel a reconnaissance flight scheduled for the 3 April because the launch area appears to be compromised. I-7 later acts as a weather ship.

3 April 1942:
Indian Ocean, 300 miles E of Maldive Islands. At 0340, I-7 attacks the 9,415-ton British motor vessel GLENSHIEL, independently en route from Bombay to Fremantle with 1,000 tons of general cargo and 12 passengers. Cdr Koizumi fires two Type 89 torpedoes; one hits GLENSHIEL's port side and the motor vessel settles by the stern. Master Ramsay Brown orders to transmit a distress signal and abandon ship. Immediately after the boats have cleared the ship, Koizumi fires two more torpedoes and gets another hit. I-7 surfaces and shells the listing vessel with her deck gun. After 20 hits, the blazing GLENSHIEL sinks by the stern at 00-48S, 78-33E. The entire crew is soon rescued by destroyer HMS FORTUNE and landed at Colombo.

5 April 1942: Operation "C" - The Raids in the Indian Ocean:
The Carrier Striking Force attacks the British naval base at Colombo, Ceylon (now Sri Lanka), wreck the base's facilities, destroy 27 aircraft and sink several ships. A floatplane finds Vice Admiral (later Admiral of the Fleet/Sir) James Somerville's Eastern Fleet's cruisers HMS CORNWALL and DORSETSHIRE at sea. Nagumo's airmen sink both ships, but are unsuccessful in their search for the rest of Somerville's fleet.

9 April 1942:
Nagumo's Striking Force attacks the British naval base at Trincomalee, Ceylon. They wreck the base's facilities and shoot down nine planes. A floatplane spots old light carrier HMS HERMES and Australian destroyer HMAS VAMPIRE at sea and the Striking Force sinks both. Nagumo's aircraft also find and sink several smaller ships.

10 April 1942:
Reassigned to Advance Force.

15 April 1942:
I-7 and I-3 arrive at Singapore.

21 April 1942:
Departs Singapore for Yokosuka.

1 May 1942:
Arrives at Yokosuka for repairs and upkeep.

5 June 1942: Operation "AL"- The Invasion of the Western Aleutians:
Twenty ships of the Vice Admiral Hosogaya Boshiro's (former CO of MUTSU) Fifth Fleet, including light cruisers KISO and TAMA, three destroyers, three corvettes, three minesweepers and four transports land Rear Admiral (later Vice Admiral) Omori Sentaro's Occupation Force on Attu, Aleutians without opposition.

7 June 1942:
Captain (later Rear Admiral) Ono Takeji's Occupation Force occupies Kiska, also without opposition.

10 June 1942:
Reassigned to the Northern Unit with I-1, I-2, I-3, I-4, I-5 and I-6.

11 June 1942:
I-7 departs Taura Bay, Yokosuka for the Aleutians on her her third patrol with I-1, I-2, I-3 and I-4. Joins the "K" patrol line and patrols off Unalaska Island, Aleutians.

14 July 1942:
N of Unalaska. Cdr Koizumi torpedoes and shells the 2,722-ton USAT freighter ARCATA (ex-GLYMONT) en route from Bethel, Alaska, to Seattle, Washington. In choppy seas the I-7's gun crew has trouble hitting their target. Once ARCATA's bridge is hit, the crew and the passengers abandon ship. I-7 ceases firing after life rafts are spotted, but not before a merchant sailor is killed. ARCATA sinks at 53-41N, 157-45W.

20 July 1942:
Reassigned to Advance Force.

1 August 1942:
Arrives at Yokosuka for an overhaul.

7 August 1942: American Operation "Watchtower" - The Invasion of Guadalcanal, British Solomon Islands:
Rear Admiral (later Admiral) Richmond K. Turner's Amphibious Task Force 62, covered by Vice Admiral (later Admiral) Frank J. Fletcher's Task Force 61 and Rear Admiral (later Admiral) John S. McCain's Task Force 63's land-based aircraft, lands Maj Gen (later Gen/Commandant) Alexander A. Vandegrift's 1st Marine Division on Guadalcanal opening a seven-month campaign to take the island.

20 August 1942:
SubRon 2 is disbanded. I-7 is directly attached to Sixth Fleet HQ.

31 August 1942:
Reassigned to SubDiv 7.

8 September 1942:
Departs Yokosuka for the Solomons with Captain Tamaki Tomejiro (ComSubDiv 7) embarked, carrying an E9W1 "Slim" seaplane.

15 September 1942:
Arrives at Truk. Reassigned to the 1st Picket Unit.

17 September 1942:
Departs Truk on her fourth war patrol with ComSubDiv 7 aboard to join a patrol line SE of San Cristobal.

10 October 1942:
I-7 is detached from the "A" patrol unit and tasked with reconnoitering Espiritu Santo prior to I-1-based Special Landing Unit's (S-Tokuriku) planned raid there.

13 October 1942:
At dawn, I-7's floatplane reconnoiters Espiritu Santo. The pilot reports seeing two light cruisers, seven transports, several smaller vessels and seaplanes off the south coast.

14 October 1942:
After nightfall, I-7 shells Espiritu Santo. She fires 17 shells.

23 October 1942:
Before dawn, I-7 again shells Espiritu Santo. She fires six shells and dives to escape return fire.

24 October 1942:
I-7 is ordered to rejoin the "A" patrol group SE of Guadalcanal.

31 October 1942:
I-7 is ordered to conduct another recce flight over Espiritu Santo, but her aircraft is damaged and she is unable to launch it.

7 November 1942:
I-7 carries out a periscopic observation of Espiritu Santo. She is relieved by I-9, carrying an E14Y1 "Glen" floatplane.

9 November 1942:
Cdr Koizumi receives an order to reconnoiter Ndeni and Vanikoro on the way back to Truk.

10 November 1942:
Cdr Koizumi carries out a periscopic observation of Ndeni. No important targets are sighted.

11 November 1942:
At dawn, I-7's floatplane reconnoiters Vanikoro Island, Santa Cruz, Solomons.

18 November 1942:
Returns to Truk.

24 November 1942:
Departs Truk for Yokosuka.

1 December 1942:
Arrives at Yokosuka.

5 December 1942:
LtCdr (Cdr, posthumously) Tabata Sunao (58)(the current CO of I-175) is appointed the CO of I-7 as an additional duty.

16 March 1943:
LtCdr (Cdr, posthumously) Nagai Katsuhiko (57)(former CO of I-174) is appointed the CO.

1 April 1943:
SubDiv 7 is reassigned to Fifth Fleet.

21 April 1943:
I-7 is assigned to reinforce and resupply the isolated Japanese garrisons in the Aleutians. Departs Yokosuka for Kiska Island carrying food and ammunition on her first supply run to that location.

1 May 1943:
Arrives at Kiska, unloads her cargo, departs on the same day for Attu.

4 May 1943:
Arrives at Attu, departs on the same day for Paramushiro.

8 May 1943:
Arrives at Paramushiro, departs on the same day for Yokosuka.

11 May 1943: American Operation "Landcrab"- The Invasion of Attu, Aleutians: Rear Admiral (later Admiral) Thomas C. Kinkaid's Task Force 16, covered by Rear Admiral Francis W. Rockwell's Task Force 51, lands elements of the Army's 4th and 7th Infantry Divisions under the command of MajGen Eugene M. Landrum at Holtz Bay and Massacre Bay that later capture the island.

12 May 1943:
Arrives at Yokosuka.

14 May 1943:
Departs Yokosuka for Attu with ComSubDiv 7 Captain Tamaki Tomejiro embarked on her second supply run-cum-combat patrol.

21 May 1943: Operation "KE-Go" - The Evacuation of Kiska:
Arrives in the area off Attu to commence her fifth war patrol. On that same day, the Imperial General Headquarters decides to abandon Attu and evacuate the garrison of Kiska.

24 May 1943:
Departs her patrol area for Kiska.

25 May 1943:
I-7 is ordered to abort the patrol and head to Kiska.

26 May 1943:
Arriving off Kiska, LtCdr Nagai finds the harbor under air attack and decides to wait outside the harbor. At 2230, I-7 enters Kiska Harbor. She delivers 6 tons of food, 13.2-mm, 8-mm and 7.7-mm ammunition and a radio beacon. For her return voyage, she embarks 49 sailors, seven soldiers and four gunzoku workers (mostly sick and wounded), plus 28 boxes of the ashes of fallen soldiers and four tons of spent shell cartridges.

27 May 1943:
Departs Kiska for Paramushiro at 0100.

1 June 1943:
Arrives at Paramushiro.

2 June 1943:
Oiler TEIYO MARU refuels I-7, I-21, I-155, I-156 and I-157.

4 June 1943:
Departs Paramushiro on her second supply run to Kiska.

8 June 1943:
I-7 and I-34 arrive at Kiska Harbor. I-7 unloads 19 tons of ammunition and 15 tons of food and then departs, carrying 101 men (42 Navy, 18 Army and 41 gunzoku workers).

13 June 1943:
Returns to Paramushiro.

15 June 1943:
At 1600, departs Paramushiro, with ComSubDiv 7 aboard, on her third supply run to Kiska.

17 June 1943:
Radar-equipped American destroyer attacks on IJN submarines in the Aleutians area and the grounding of I-175 cause ComSubRon 1 to order I-7, I-34, I-36 and I-169 to suspend their supply missions and await further orders. I-2, I-157 and I-175 are tasked to determine the exact location of the American ships.

18 June 1943:
ComSubRom 1 orders the resumption of the supply missions to Kiska.

19 June 1943:
I-7 makes a landfall off Kiska, but LtCdr Nagai decides not to enter Gertrude Cove in Vega Bay because of a dense fog. He contacts the 51st Base Unit on Kiska and learns that the local radio beacon will be deactivated after 0500, 20 June.

20 June 1943:
At 1900, I-7 surfaces in heavy fog approximately one mile S of Vega Bay and heads towards the anchorage. Twenty minutes later her sound operator reports propeller noises starboard, bearing 050. Captain Tamaki who has the conn, orders prepare for diving.

LtCdr Peter H. Horn's USS MONAGHAN (DD-354) patrolling two miles off Bukhti Point, picks up the submarine on her SG radar at 14,000 yards and tracks it. One mile S of the anchorage, MONAGHAN opens radar-directed fire from 2,000 yards distance.

About 1930, the first shot is heard; Captain Tamaki orders a crash-dive. Immediately thereafter, I-7 takes two 5-inch shell hits holing her conning tower from starboard. Capt Tamaki, LtCdr Nagai, navigating officer Lt Hanabusa Yoshio, the helmsman and two NCOs are killed and the communications officer wounded.

Torpedo officer Lt Sekiguchi Rokuro assumes command. He aborts the order to dive and sends up the gun crews. I-7 returns fire with her 14-cm deck guns and 13.2 mm machine guns, firing about 30 shells and 250 machine gun rounds. As a result of confusion the aft ballast tanks valves remain open and the submarine develops a serious list. Around 1945, I-7, down by the stern, runs aground at Bukhti Point; Lt Sekiguchi orders Abandon Ship. I-7's paymaster destroys all secret documents, smashes the coding machine and throws its pieces overboard.

Earlier, the 51th Base Force had sent a Daihatsu barge to unload I-7's cargo. Sailing in the thick fog, the crew of the barge attempts to contact I-7 with a blinker gun. Instead, she receives a hail of machine-gun fire from MONAGHAN which spotted this new target 40 minutes after her last shot at I-7. The barge doubles back.

21 June 1943:
By 0200, the crew of I-7 establishes contact with shore units, using a portable transmitter. Two Daihatsu barges arrive from Gertrude Cove to embark I-7's cargo.

Lt Sekiguchi convenes a meeting of surviving officers, suggesting a surfaced flank speed run to Yokosuka with a stop at Paramushiro if necessary. The holes in the conning tower are welded shut, using a welding apparatus delivered by one of the barges.

By 1845, the makeshift repairs are completed and by 1900 the submarine enters Gertrude Cove to unload the rest of her cargo and the bodies of personnel KIA. I-7's paymaster receives two JN-25 coding books from the local 51st Naval Communications Unit to communicate with IJN units on Paramushiro.

At 2400, I-7 conned by Lt Sekiguchi, departs Vega Bay.

22 June 1943:
At 0035, MONAGHAN, patrolling S of Kiska, picks up a surface target 14,000 yards away. She closes and opens fire at 0230.

In the midst of heavy fog, I-7 comes under fire and again receives several hits to her conning tower (this time from port side), deck gun bulwark and aft ballast tanks. The acting CO is severely wounded and the engineering officer Lt Handa Masao is killed. Confused lookouts report I-7 is targeted by no less than three separate ships from different directions.

Gunnery officer Lt(jg) Shindo Yoshio assumes command and orders to return fire from deck guns and machine guns. Lookouts spot what they take to be a small fire on one of the attackers. Ten minutes later, MONAGHAN checks fire.

At 0210, the destroyer resumes fire at the same target, illuminating it with starshells. Around 0218, one shell disables I-7's steering engine and the submarine commences a wide turn port, towards Kiska. Her gun crews are rotated four times during the engagement, firing 70 main caliber shells and about 2,000 machine-gun rounds. Another hit detonates the ready-use ammunition of the deck gun, starting a small fire. The flames are sucked into diesel engine ventilation intakes, endangering the galley and the forward head. Two more shells hole the aft deck casing on the port side, so that I-7 develops a 30-degree list.

At 0230 Lt(jg) Shindo orders I-7 to return to Kiska. MONAGHAN, nearing the rocks off Kiska, breaks off the chase.

Around 0310, I-7 contacts the 51st Base Unit, reporting her damage and estimated time of arrival. Five minutes later, I-7 runs aground on the Twin Rocks off Vega Bay at 51-49N, 177-20E, foundering rapidly by the stern. Several sailors are trapped inside the submarine; a bag containing code books and other secret documents is left suspended on a ladder at her No. 3 after access hatch. Only fifty feet of the bow protrude out of the water.

At 0630, a Daihatsu evacuates all 43 survivors (including 10 wounded, one dies later). A total of 87 officers and crewmen are killed.

23 June 1943:
A Daihatsu from Kiska scuttles the bow of I-7 in the midst of the fog, using demolition charges. Divers attempt to locate the code books prior to the scuttling, but fail to retrieve them.

20 August 1943:
Removed from the Navy List.

26 August 1943:
Fleet tug USS UTE (ATF-76) is sent to investigate the reported sinking. Her divers find the submarine lying on her port side in 10 fathoms of water. The conning tower is damaged, but I-7's hull number is visible on a tarp on the side of the conning tower.

7 September 1943:
Submarine rescue ship USS FLORIKAN (ASR-9) arrives at Kiska from Midway. She carries out a month-long diving operation on I-7's hulk. Seven divers enter the submarine and recover important intelligence documents.

Authors' Notes:
[1] Mt. Niitaka, located in Formosa (now Taiwan), is then the highest point in the Japanese Empire.

[2] A recent theory claims that the floatplane from I-7 managed to down an Oahu-based PBY Catalina off Niihau. This is not confirmed by Japanese sources; in fact, I-7's floatplane did not encounter any aircraft throughout its flight, nor did it reconnoiter the Niihau area. While some sources identify that floatplane as the E14Y1 Type 0 "Glen", the I-7 class was not capable of embarking that model, not compatible with the older type twin aircraft storage tubes.

[3] According to older sources, only I-8 was fitted with a twin 140-mm (5.5-in) deck gun, but photos show the twin gun armament fitted to both I-7 and I-8, a fact also confirmed by multiple survivor reports.

[4] I-7's attacker was probably a "Catalina I" of RAF No. 205 Squadron.

Thanks go to Dr. Higuchi Tatsuhiro of Japan. Thanks also go to Jan "Visje” Visser of the Netherlands for his research of the Dutch ships involved and to James C. Sawruk of the USA and Rob Stuart of Canada for the RAF Catalina episode.

- Bob Hackett and Sander Kingsepp.

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