HMCS Grou

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 Flower-class corvette was a British class of 294 corvettes used during World War II by the Allied navies particularly as anti-submarine convoy escorts in the Battle of the Atlantic. Royal Navy ships of this class were named after flowers.

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.

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.

Halifax is the capital and largest municipality of the Canadian province of Nova Scotia, and the largest municipality in Atlantic Canada. Halifax is one of Canada's fastest growing municipalities, and as of 2022, it is estimated that the CMA population of Halifax was 480,582, with 348,634 people in its urban area. The regional municipality consists of four former municipalities that were amalgamated in 1996: Halifax, Dartmouth, Bedford, and Halifax County.

Derry, officially Londonderry, 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.

Kola Bay or Murmansk Fjord is a 57-km-long fjord of the Barents Sea that cuts into the northern part of the Kola Peninsula. It is up to 7 km wide and has a depth of 200 to 300 metres. The Tuloma, Rosta and Kola Rivers discharge into the bay.

Portsmouth is a port and city in the ceremonial county of Hampshire in southern England. The city of Portsmouth has been a unitary authority since 1 April 1997 and is administered by Portsmouth City Council.

Plymouth is a port city and unitary authority in South West England. It is located on the south coast of Devon, approximately 36 miles (58 km) south-west of Exeter and 193 miles (311 km) south-west of London. It is bordered by Cornwall to the west and south-west.

Dartmouth is an urban community and former city located in the Halifax Regional Municipality of Nova Scotia, Canada. Dartmouth is located on the eastern shore of Halifax Harbour. Dartmouth has been nicknamed the City of Lakes, after the large number of lakes located within its boundaries.

Victoria is the capital city of the Canadian province of British Columbia, on the southern tip of Vancouver Island off Canada's Pacific coast. The city has a population of 91,867, and the Greater Victoria area has a population of 397,237. The city of Victoria is the 7th most densely populated city in Canada with 4,405.8 inhabitants per square kilometre (11,411/sq mi).