Japanese submarine I-12

A squadron, or naval squadron, is a significant group of warships which is nonetheless considered too small to be designated a fleet. A squadron is typically a part of a fleet. Between different navies there are no clear defining parameters to distinguish a squadron from a fleet, and the size and strength of a naval squadron varies greatly according to the country and time period. Groups of small warships, or small groups of major warships, might instead be designated flotillas by some navies according to their terminology. Since the size of a naval squadron varies greatly, the rank associated with command of a squadron also varies greatly.

A flagship is a vessel used by the commanding officer of a group of naval ships, characteristically a flag officer entitled by custom to fly a distinguishing flag. Used more loosely, it is the lead ship in a fleet of vessels, typically the first, largest, fastest, most heavily armed, or best known.

The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, tonnes are more commonly used.

The beam of a ship is its width at its widest point. The maximum beam (BMAX) is the distance between planes passing through the outer extremities of the ship, beam of the hull (BH) only includes permanently fixed parts of the hull, and beam at waterline (BWL) is the maximum width where the hull intersects the surface of the water.

The draft or draught of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel). The draught of the vessel is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed. Draft determines the minimum depth of water a ship or boat can safely navigate. The related term air draft is the maximum height of any part of the vessel above the water.

The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is called a compression-ignition engine. This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine or a gas engine.

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates with a reversed flow of power, converting mechanical energy into electrical energy.

The knot is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h. The ISO standard symbol for the knot is kn. The same symbol is preferred by the Institute of Electrical and Electronics Engineers (IEEE), while kt is also common, especially in aviation, where it is the form recommended by the International Civil Aviation Organization (ICAO). The knot is a non-SI unit. The knot is used in meteorology, and in maritime and air navigation. A vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour.

A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such a device was called an automotive, automobile, locomotive, or fish torpedo; colloquially a fish. The term torpedo originally applied to a variety of devices, most of which would today be called mines. From about 1900, torpedo has been used strictly to designate a self-propelled underwater explosive device.

The 14 cm/40 11th Year Type naval gun was the standard surface battery for Japanese submarine cruisers of World War II. Most carried single guns, but Junsen type submarines carried two. Japanese submarines I-7 and I-8 carried an unusual twin mounting capable of elevating to 40°. The appended designation 11th year type refers to the horizontal sliding breech block on these guns. Breech block design began in 1922, or the eleventh year of the Taishō period in the Japanese calendar. The gun fired a projectile 14 centimeters (5.5 in) in diameter, and the barrel was 40 calibers long.

A deck gun is a type of naval artillery mounted on the deck of a submarine. Most submarine deck guns were open, with or without a shield; however, a few larger submarines placed these guns in a turret.

Kawasaki Heavy Industries Ship & Offshore Structure Company is the shipbuilding subsidiary of Kawasaki Heavy Industries. It produces primarily specialized commercial vessels, including LNG carriers, LPG carriers, container ships, bulk carriers, oil tankers, as well as high speed passenger jetfoils. In addition, it is also a producer of warships for the Japan Maritime Self-Defense Force, including submarines. Kawasaki also produces marine machinery, including marine engines, thrusters, steering gears, deck and fishing machinery.

Kobe is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, which makes up the southern side of the main island of Honshū, on the north shore of Osaka Bay. It is part of the Keihanshin metropolitan area along with Osaka and Kyoto. The Kobe city centre is located about 35 km (22 mi) west of Osaka and 70 km (43 mi) southwest of Kyoto.

Japan is an island country in East Asia. It is situated in the northwest Pacific Ocean and is bordered on the west by the Sea of Japan, extending from the Sea of Okhotsk in the north toward the East China Sea, Philippine Sea, and Taiwan in the south. Japan is a part of the Ring of Fire, and spans an archipelago of 14,125 islands covering 377,975 square kilometers (145,937 sq mi); the five main islands are Hokkaido, Honshu, Shikoku, Kyushu, and Okinawa. Tokyo is the nation's capital and largest city, followed by Yokohama, Osaka, Nagoya, Sapporo, Fukuoka, Kobe, and Kyoto.

Yokosuka Naval District was the first of four main administrative districts of the pre-war Imperial Japanese Navy. Its territory included Tokyo Bay and the Pacific coasts of central and northern Honshū from the Kii Peninsula to Shimokita Peninsula. Its headquarters, along with most of its installations, including the Yokosuka Naval Arsenal, were located in the city of Yokosuka, which constituted the Yokosuka Naval Base.

Ceremonial ship launching involves the performance of ceremonies associated with the process of transferring a vessel to the water. It is a nautical tradition in many cultures, dating back thousands of years, to accompany the physical process with ceremonies which have been observed as public celebration and a solemn blessing, usually but not always, in association with the launch itself.

The 6th Fleet was a fleet of the Imperial Japanese Navy (IJN) that during World War II, had primary responsibility for the command of submarine operations.

Kobe is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, which makes up the southern side of the main island of Honshū, on the north shore of Osaka Bay. It is part of the Keihanshin metropolitan area along with Osaka and Kyoto. The Kobe city centre is located about 35 km (22 mi) west of Osaka and 70 km (43 mi) southwest of Kyoto.

The Combined Fleet was the main sea-going component of the Imperial Japanese Navy. Until 1933, the Combined Fleet was not a permanent organization, but a temporary force formed for the duration of a conflict or major naval maneuvers from various units normally under separate commands in peacetime.

The Allies, formally referred to as the United Nations from 1942, were an international military coalition formed during the Second World War (1939–1945) to oppose the Axis powers, led by Nazi Germany, Imperial Japan, and Fascist Italy. Its principal members by the end of 1941 were the United Kingdom, United States, Soviet Union, and China.

Sea lines of communication is a term describing the primary maritime routes between ports, used for trade, logistics and naval forces. It is generally used in reference to naval operations to ensure that SLOCs are open, or in times of war, to close them. The importance of SLOCs in geopolitics was described in Nicholas J. Spykman's America's Strategy in World Politics published in 1942.

Hawaii is a state in the Western United States, about 2,000 miles (3,200 km) from the U.S. mainland in the Pacific Ocean. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state in the tropics.

The Hawaiian Islands are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaiʻi in the south to northernmost Kure Atoll. Formerly the group was known to Europeans and Americans as the Sandwich Islands, a name that James Cook chose in honor of the 4th Earl of Sandwich, the then First Lord of the Admiralty. Cook came across the islands by chance when crossing the Pacific Ocean on his Third Voyage in 1778, on board HMS Resolution; he was later killed on the islands on a return visit. The contemporary name of the islands, dating from the 1840s, is derived from the name of the largest island, Hawaiʻi Island.

The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south, and is bounded by the continents of Asia and Oceania in the west and the Americas in the east.

The Marshall Islands, officially the Republic of the Marshall Islands, is an island country and microstate near the Equator in the Pacific Ocean, slightly west of the International Date Line. Geographically, the country is part of the larger island group of Micronesia.

Hakodate is a city and port located in Oshima Subprefecture, Hokkaido, Japan. It is the capital city of Oshima Subprefecture. As of July 31, 2011, the city has an estimated population of 279,851 with 143,221 households, and a population density of 412.83 persons per km2. The total area is 677.77 square kilometres (261.69 sq mi). The city is the third biggest in Hokkaido after Sapporo and Asahikawa.

Liberty ships were a class of cargo ship built in the United States during World War II under the Emergency Shipbuilding Program. Though British in concept, the design was adopted by the United States for its simple, low-cost construction. Mass-produced on an unprecedented scale, the Liberty ship came to symbolize U.S. wartime industrial output.

San Francisco, officially the City and County of San Francisco, is a commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California, with 815,201 residents as of 2021, and covers a land area of 46.9 square miles, at the end of the San Francisco Peninsula, making it the second most densely populated large U.S. city after New York City and the fifth most densely populated U.S. county, behind only four of the five New York City boroughs. Among the 91 U.S. cities proper with over 250,000 residents, San Francisco was ranked first by per capita income and sixth by aggregate income as of 2021. Colloquial nicknames for San Francisco include SF, San Fran, The City, Frisco, and Baghdad by the Bay.