Submarines have always been dangerous.

The early submarines were even more so because of the emerging technologies that had not yet evolved. The men who rode the early boats were a different breed. This story is about one of them who was a national hero in Japan and left a legacy that would have implications for decades to come. The story is about the Last Letter he ever wrote to his father. It is certainly a letter no submariner’s father ever wants to receive.

The beginning of the Japanese Submarine Fleet had its roots in America

The Imperial Japanese Navy (IJN) acquired its first submarines during the Russo-Japanese War on 12 December 1904 where they arrived in sections at the Yokohama dockyards. The vessels were purchased from the relatively new American company, Electric Boat, and were fully assembled and ready for combat operations by August 1905. However, hostilities with Russia were nearing its end by that date, and no submarines saw action during the war.

The submarines that Electric Boat sold to Japan were based on the Holland designs, known as Holland Type VIIs similar to the American Plunger-class submarines. The five imported Hollands were originally built at Fore River Ship and Engine Company in Quincy, Massachusetts under Busch’s direction for the Electric Boat Company back in August–October 1904. They were shipped by freighter from Seattle, Washington in Knock-down kit form to Japan, and then reassembled by Arthur Leopold Busch at the Yokosuka Naval Arsenal, which was then Japan’s largest naval shipyard, to become Hulls No. 1 through 5 and were designated Type 1 submarines by the Japanese Navy.

Frank Cable, an electrician who was working for Isaac Rice’s Electro-Dynamic and Storage Companies along with Rice’s Electric Boat, arrived some six months after Busch, training the IJN in the operation of the newly introduced vessels.

In 1904 Kawasaki Dockyard Company purchased plans for a modified version directly from Holland, and built two boats (Hulls No. 6 and 7), with the help of two American engineers, Chase and Herbert, who had been assistants to Holland. The Kawasaki-type submarines displaced 63 and 95 tons when submerged, and measured 73 and 84 feet in overall length, respectively. Both vessels measured 7 feet at the beam. This contrasted with the original five imported Holland type submarines which had arrived that same year, at over 100 tons submerged, 67 feet in overall length and 11 feet beam. The Kawasaki Type #6 and #7 submarines had gained extra speed and reduced fuel consumption by 1/4. However both boats could launch only one 18″ torpedo, and each was manned by 14 sailors, whereas the imported Holland-type submarines could fire two torpedoes and could be operated by 13 sailors. This new type was designated the Type 6 submarine by the Japanese Navy, and was used primarily for test purposes.

The Kaigun Holland #6 was launched at Kobe on 28 September 1905 and was completed six months later at Kure as the first submarine built in Japan. It sank during a training dive in Hiroshima Bay on 15 April 1910. Although the water was only 58 feet deep, there were no provisions at all for the crew to escape while submerged. The commanding officer, Lieutenant Tsutomu Sakuma, patiently wrote a description of his sailor’s efforts to bring the boat back to the surface as their oxygen supply ran out. All of the sailors were later found dead at their duty stations when this submarine was raised the following day. The sailors were regarded as heroes for their calm performance of their duties until death, and this submarine has been preserved as a memorial in Kure, Japan

SINKING OF JAPANESE SUBMARINE No. 6

When the Japanese submarine No. 6, which foundered while maneuvering in Hiroshima Bay on April 16, was raised, the following message was found. It was written by Lieut. Tsutoma Sakuma, the commander, after it became evident that the submarine could not be raised by the efforts of the crew. The translation appeared in the Kobe Herald, and is as follows:

Although there is, indeed, no excuse to make for the sinking of His Imperial Majesty’s boat and for the doing away of subordinates through my heedlessness, all on the boat have discharged their duties well, and in everything acted calmly until death. Although we are departing in pursuance of our duty to the State, the only regret we have is due to anxiety lest the then of the world may misunderstand the matter, and that thereby a blow may be given to the future development of submarines. Gentlemen, we hope you will be increasingly diligent without misunderstanding (the cause of this accident), and that you will devote your full strength to investigate everything, and so insure the future development of submarines. If this is done we shall have nothing to regret.

While going through gasoline submarine exercises we submerged too far, and when we attempted to shut the sluice valve the chain in the meantime gave way. Then we tried to close the sluice valve by hand, but it was then too late, the rear part being full of water, and the boat sank at an angle of about 25 degrees. –

The boat rested at an incline of above 13 degrees, pointing towards the stern. The switchboard being under water, the electric lights gave out. Offensive gas developed, and respiration became difficult.

At about 10 a. m. on the 15th the boat sank, and under this offensive gas we endeavored to expel the water with a hand pump.

At the same time as the vessel was being submerged, we expelled the water from the main tank. The light having gone out the gauge cannot be seen, but we know that the water has been expelled from the main tank. We cannot use the electric current entirely The electric liquid is overflowing, but no salt water has entered, and chlorine gas has not developed.

We only rely upon the hand pump now. The above has been written under the light of the conning tower, when it was 1145 o’clock. We are now soaked by the water that has made its way in. Our clothes are pretty wet and we feel cold.

I had always been used to warn my shipmates that their behavior (on an emergency) should be calm and delicate while brave; otherwise we could not hope for development and progress, and that, at the same time, one should not cultivate excessive delicacy lest work should be retarded. People may be tempted to ridicule this after this failure, but I am perfectly confident that my previous words have not been mistaken.

The depth gauge of the conning tower indicates 52, and despite the endeavor to expel the water, the pump stopped, and did not work after twelve o’clock. The depth in this neighborhood being ten fathoms the reading may be correct.

The officers and men of submarines must be appointed from the most distinguished among the distinguished, or there will be annoyance in cases like this. Happily all the members of this crew have discharged their duties well, and I feel satisfied.

I have always expected death whenever I left my home, and therefore my will is already in the drawer at Karasaki. (This remark refers only to my private affairs, and it is not necessary.

Messrs. Taguchi and Asami ! Please inform my father of this.)

I respectfully beg to say to His Majesty, I respectfully request that none of the families left by my subordinates shall suffer. The only thing I am anxious about now is this.

Please convey my compliments to the following gentlemen:

(the order may not be proper) : —Minister Saito; Vice-Admiral Shimamura; Vice-Admiral Fujii; Rear-Admiral Nawa; Rear Admiral Yamashita; Rear-Admiral Narita. (Atmospheric pressure is increasing, and I feel as if my tympanum were breaking.)

Captain Oguri; Captain Ide; Commander Matsumura (Junichi); Captain Matsumura (Riu); Commander Matsumura (Kiku) —my elder brother. Captain Funakoshi; Instructor Narita Kotaro; Instructor Ikuta Kokinji. –

12.30 o’clock, respiration is extraordinarily difficult. I mean I am breathing gasoline. I am intoxicated with gasoline.

Captain Nakano

It is 12.40 o’clock.

After the submarine was lifted from the sea, the tone soon changed to praise of Sakuma and his crew for the glorious way they died while carrying out their duty.

Lt. Sakuma was in the conning tower, just as he had been when commanding his crew in majestic fashion, but instead lying in eternal repose as though still alive. The helmsman had expired with his hand still on the handle of the rudder … That they kept their composure is the mark of military men, and their devotion to the duty in the face of death is moving in the extreme. *

* Tokyo Asahi Shimbun, April 20, 1910. Furthermore, in the Kobunbiko Maki 26-2, Dairoku Sensuitei Sounanji ni Okeru Teinai Eisei Jokyo ni Kansuru Chosahokoku (Report on the Conditions Inside the Vessel at the Time of the Submarine No. 6 Accident), Lt. Sakuma is described as having been found at the aft side of the bottom of the conning tower.

The newspapers published a copy of his original letter. The original letter was stored at the Kure Naval Shipyard and was destroyed in a fire during the Great Kanto Earthquake.