7th January 1942: First confirmed sinking of a Japanese vessel by a US submarine.

USS Pollack was the first US submarine to reach Japanese waters. She had departed from Pearl Harbor on 31st December 1941. The Pollack seriously damaged a cargo ship on 5th January 1942. Then, on 7th January 1942, the UNKAI MARU No. 1 was spotted. The Pollack attacked using torpedos.

The torpedo disabled the UNKAI MARU No. 1, causing water to start seeping into the vessel and cutting off her engines. A nearby vessel responded to calls for assistance and 53 men transferred onto the MEITEN MARU.

The MEITEN MARU attempted to tow thr Unkai Maru No. 1 to a port but the damage was too great. The Unkai Naru No. 1 sank as a result.

Below is a summary of the service record of the Unkai Maru No. 1.

28 September 1941:

Requisitioned by the IJN.

1 December 1941: Arrives at Tama. Registered as an auxiliary collier, Otsu category, attached to the Sasebo Naval District under instruction No. 1573. [1]

2 December 1941:

Conversion for military duty starts at Mitsui Bussan Zosenbu K.K. shipyard.

17 December 1941:

Departs Tama.

18 December 1941:

Arrives at Kure. Departs there later that day.

19 December 1941:

Arrives at Tokuyama. Departs there later that same day.

20 December 1941:

Arrives at Wakamatsu.

21 December 1941:

Arrives at Shimonoseki. Departs there later in the day.

22 December 1941:

Arrives at Sasebo.

28 December 1941:

The conversion is completed.

29 December 1941:

Departs Sasebo.

30 December 1941:

Arrives at Kure.

31 December 1941:

Departs Kure.

1 January 1942:

Arrives at Tokuyama.

2 January 1942:

Departs Tokuyama.

5 January 1942:

Arrivers at Yokosuka. Departs there later that day possibly with MEITEN and AKASHISAN MARUs.

7 January 1942:

At 0755, torpedoed by LtCdr (later Captain) Stanley P. Moseley’s (USNA ‘25) USS POLLACK (SS-180) off Miko lighthouse; the ship is hit by one torpedo and disabled at 34-27N, 138-59E. One crewman is KIA. IJN auxiliary transport MEITEN MARU arrives and rescues 53 people. Later that day, MEITEN MARU starts towing UNKAI MARU No. 1 but strong wind and high waves break the towing line. UNKAI MARU NO. 1 is left drifting.