HMCS Charlottetown (1943)

The River class was a class of 151 frigates launched between 1941 and 1944 for use as anti-submarine convoy escorts in the North Atlantic. The majority served with the Royal Navy and Royal Canadian Navy (RCN), with some serving in the other Allied navies: the Royal Australian Navy (RAN), the Free French Naval Forces, the Royal Netherlands Navy and, post-war, the South African Navy.

The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against France. The modern Royal Navy traces its origins to the early 16th century; the oldest of the UK's armed services, it is consequently known as the Senior Service.

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many smaller islands within the British Isles. Northern Ireland shares a land border with the Republic of Ireland; otherwise, the United Kingdom is surrounded by the Atlantic Ocean, the North Sea, the English Channel, the Celtic Sea and the Irish Sea. The total area of the United Kingdom is 242,495 square kilometres (93,628 sq mi), with an estimated 2023 population of over 68 million people.

U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic-warfare role and enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada and other parts of the British Empire, and from the United States, to the United Kingdom and to the Soviet Union and the Allied territories in the Mediterranean. German submarines also targeted Brazilian merchant ships during both World Wars and, twice over, precipitated Brazil's decision to give up its neutral stance and declare war on Germany.

HMCS Valleyfield was a River-class frigate that served with the Royal Canadian Navy during the Second World War. She served primarily as a convoy escort in the Battle of the Atlantic. She was torpedoed and sunk in May 1944, the only River-class frigate lost by the RCN. She was named for Salaberry-de-Valleyfield, Quebec.

The Hedgehog was a forward-throwing anti-submarine weapon that was used primarily during the Second World War. The device, which was developed by the Royal Navy, fired up to 24 spigot mortars ahead of a ship when attacking a U-boat. It was deployed on convoy escort warships such as destroyers and corvettes to supplement the depth charges.

The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes, which are Superior, Michigan, Huron, Erie, and Ontario and are in general on or near the Canada–United States border. Hydrologically, lakes Michigan and Huron are a single body joined at the Straits of Mackinac. The Great Lakes Waterway enables modern travel and shipping by water among the lakes.

The St. Lawrence River is a large river in the middle latitudes of North America. Its headwaters begin flowing from Lake Ontario in a roughly northeasterly direction, into the Gulf of St. Lawrence, connecting the North American Great Lakes to the North Atlantic Ocean, and forming the primary drainage outflow of the Great Lakes Basin. The river traverses the Canadian provinces of Ontario and Quebec, as well as the U.S. state of New York, and demarcates part of the international boundary between Canada and the United States. It also provides the foundation for the commercial St. Lawrence Seaway.

The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage of its active battle fleet alone exceeding the next 13 navies combined, including 11 allies or partner nations of the United States as of 2015. It has the highest combined battle fleet tonnage and the world's largest aircraft carrier fleet, with eleven in service, two new carriers under construction, and five other carriers planned. With 336,978 personnel on active duty and 101,583 in the Ready Reserve, the United States Navy is the third largest of the United States military service branches in terms of personnel. It has 290 deployable combat vessels and more than 2,623 operational aircraft as of June 2019.

Bermuda is a British Overseas Territory in the North Atlantic Ocean. The Bermuda archipelago consists of 181 islands with a total land area of 54 km2 (21 sq mi). The closest land outside the territory is in the US state of North Carolina, approximately 1,035 km (643 mi) to the northwest.

Derry, officially Londonderry,(Irish: Doire), is the second-largest city in Northern Ireland and the fifth-largest city on the island of Ireland. The old walled city lies on the west bank of the River Foyle, which is spanned by two road bridges and one footbridge. The city now covers both banks.

Northern Ireland is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Northern Ireland shares an open border to the south and west with the Republic of Ireland. In 2021, its population was 1,903,100, making up about 27% of Ireland's population and about 3% of the UK's population. The Northern Ireland Assembly, established by the Northern Ireland Act 1998, holds responsibility for a range of devolved policy matters, while other areas are reserved for the UK Government. The government of Northern Ireland cooperates with the government of the Republic of Ireland in several areas agreed under the terms of the Belfast Agreement. The Republic of Ireland also has a consultative role on non-devolved governmental matters through the British-Irish Governmental Conference (BIIG).

Gibraltar is a British Overseas Territory and city located at the southern tip of the Iberian Peninsula. It has an area of 6.7 km2 (2.6 sq mi) and is bordered to the north by Spain. The landscape is dominated by the Rock of Gibraltar, at the foot of which is a densely populated town area, home to over 32,000 people, primarily Gibraltarians.

Royal Canadian Navy base HMCS Protector, also known as the Point Edward Naval Base, was located next to Sydney Harbour, on Nova Scotia's Cape Breton Island. It was founded in 1940 and used by the navy during the Second World War. It was mainly used to provision, protect and repair the various merchant marine convoys to Quebec, Halifax, and the United Kingdom. It was a main combat zone during the Battle of the St. Lawrence and the more general Battle of the Atlantic. It continued to be utilized during the Cold War's early stages. It was decommissioned in 1964 and became the initial facility to house the Canadian Coast Guard College that same year. Currently, the Sydport Industrial Park utilizes the base's former piers and land.

Sydney is a former city and urban community on the east coast of Cape Breton Island in Nova Scotia, Canada within the Cape Breton Regional Municipality. Sydney was founded in 1785 by the British, was incorporated as a city in 1904, and dissolved on 1 August 1995, when it was amalgamated into the regional municipality.

Operation Downfall was the proposed Allied plan for the invasion of the Japanese home islands near the end of World War II. The planned operation was canceled when Japan surrendered following the atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and the invasion of Manchuria. The operation had two parts: Operation Olympic and Operation Coronet. Set to begin in November 1945, Operation Olympic was intended to capture the southern third of the southernmost main Japanese island, Kyūshū, with the recently captured island of Okinawa to be used as a staging area. In early 1946 would come Operation Coronet, the planned invasion of the Kantō Plain, near Tokyo, on the main Japanese island of Honshu. Airbases on Kyūshū captured in Operation Olympic would allow land-based air support for Operation Coronet. If Downfall had taken place, it would have been the largest amphibious operation in history, surpassing D-Day.

The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, bringing the war's hostilities to a close. By the end of July 1945, the Imperial Japanese Navy (IJN) had become incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of the Japanese armed forces in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction". While publicly stating their intent to fight on to the bitter end, Japan's leaders were privately making entreaties to the publicly neutral Soviet Union to mediate peace on terms more favorable to the Japanese. While maintaining a sufficient level of diplomatic engagement with the Japanese to give them the impression they might be willing to mediate, the Soviets were covertly preparing to attack Japanese forces in Manchuria and Korea in fulfillment of promises they had secretly made to the United States and the United Kingdom at the Tehran and Yalta Conferences.