Mid-Ocean Escort Force

World War I or the First World War, often abbreviated as WWI, was one of the deadliest global conflicts in history. It was fought between two coalitions, the Allies and the Central Powers. Fighting occurred throughout Europe, the Middle East, Africa, the Pacific, and parts of Asia. An estimated 9 million soldiers were killed in combat, plus another 23 million wounded, while 5 million civilians died as a result of military action, hunger, and disease. Millions more died as a result of genocide, while the 1918 Spanish flu pandemic was exacerbated by the movement of combatants during the war.

Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of Norway. Bouvet Island, located in the Subantarctic, is a dependency of Norway; it also lays claims to the Antarctic territories of Peter I Island and Queen Maud Land. The capital and largest city in Norway is Oslo.

Halifax Harbour is a large natural harbour on the Atlantic coast of Nova Scotia, Canada, located in the Halifax Regional Municipality. Halifax largely owes its existence to the harbour, being one of the largest and deepest ice-free natural harbours in the world. Before Confederation it was one of the most important commercial ports on the Atlantic seaboard. In 1917, it was the site of the world's largest man-made accidental explosion, when the SS Mont-Blanc blew up in the Halifax Explosion of December 6.

Newfoundland is a large island off the east coast of the North American mainland and the most populous part of the Canadian province of Newfoundland and Labrador. It has 29 percent of the province's land area. The island is separated from the Labrador Peninsula by the Strait of Belle Isle and from Cape Breton Island by the Cabot Strait. It blocks the mouth of the Saint Lawrence River, creating the Gulf of Saint Lawrence, the world's largest estuary. Newfoundland's nearest neighbour is the French overseas collectivity of Saint Pierre and Miquelon.

Iceland is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which is home to about 36% of the population. Iceland is the largest part of the Mid-Atlantic Ridge that rises above sea level, and its central volcanic plateau is erupting almost constantly. The interior consists of a plateau characterised by sand and lava fields, mountains, and glaciers, and many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence keep summers chilly, and most of its islands have a polar climate.

The Western Approaches is an approximately rectangular area of the Atlantic Ocean lying immediately to the west of Ireland and parts of Great Britain. Its north and south boundaries are defined by the corresponding extremities of Britain. The coast of the mainland forms the eastern side and the western boundary is the 30 degree meridian, which passes through Iceland. The area is particularly important to the United Kingdom, because many of its larger shipping ports lie within it.

Franklin Delano Roosevelt, commonly known as FDR, was an American statesman and political leader who served as the 32nd president of the United States from 1933 until his death in 1945. A Democrat, he previously served as the 44th governor of New York from 1929 to 1933, the Assistant Secretary of the Navy from 1913 to 1920, and a member of the New York State Senate from 1911 to 1913.

Iceland is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which is home to about 36% of the population. Iceland is the largest part of the Mid-Atlantic Ridge that rises above sea level, and its central volcanic plateau is erupting almost constantly. The interior consists of a plateau characterised by sand and lava fields, mountains, and glaciers, and many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence keep summers chilly, and most of its islands have a polar climate.

The HX convoys were a series of North Atlantic convoys which ran during the Battle of the Atlantic in the Second World War. They were east-bound convoys and originated in Halifax, Nova Scotia from where they sailed to ports in the United Kingdom. They absorbed the BHX convoys from Bermuda en route. Later, after the United States entered the war, HX convoys began at New York.

The Royal Canadian Navy is the naval force of Canada. The RCN is one of three environmental commands within the Canadian Armed Forces. As of 2021, the RCN operates 12 frigates, four attack submarines, 12 coastal defence vessels, eight patrol class training vessels, two offshore patrol vessels, and several auxiliary vessels. The RCN consists of 8,570 Regular Force and 4,111 Primary Reserve sailors, supported by 3,800 civilians. Vice-Admiral Angus Topshee is the current commander of the Royal Canadian Navy and chief of the Naval Staff.

The River class was a class of fourteen destroyers of the Royal Canadian Navy (RCN) that served before and during the Second World War. They were named after Canadian rivers.

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.

A corvette is a small warship. It is traditionally the smallest class of vessel considered to be a proper warship. The warship class above the corvette is that of the frigate, while the class below was historically that of the sloop-of-war.

The Gleaves-class destroyers were a class of 66 destroyers of the United States Navy built 1938–42, designed by Gibbs & Cox. The first ship of the class was USS Gleaves. They were the destroyer type that was in production for the US Navy when the United States entered World War II.

Great-circle navigation or orthodromic navigation is the practice of navigating a vessel along a great circle. Such routes yield the shortest distance between two points on the globe.

Newfoundland is a large island off the east coast of the North American mainland and the most populous part of the Canadian province of Newfoundland and Labrador. It has 29 percent of the province's land area. The island is separated from the Labrador Peninsula by the Strait of Belle Isle and from Cape Breton Island by the Cabot Strait. It blocks the mouth of the Saint Lawrence River, creating the Gulf of Saint Lawrence, the world's largest estuary. Newfoundland's nearest neighbour is the French overseas collectivity of Saint Pierre and Miquelon.

The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, and over six thousand smaller islands. They have a total area of 315,159 km2 (121,684 sq mi) and a combined population of almost 72 million, and include two sovereign states, the Republic of Ireland, and the United Kingdom of Great Britain and Northern Ireland. The Channel Islands, off the north coast of France, are normally taken to be part of the British Isles, even though they do not form part of the archipelago.

St. John's is the capital and largest city of the Canadian province of Newfoundland and Labrador, located on the eastern tip of the Avalon Peninsula on the island of Newfoundland.

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.

Hvalfjörður is situated in the west of Iceland between Mosfellsbær and Akranes. The fjord is approximately 30 km long and 5 km wide.

Iceland is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which is home to about 36% of the population. Iceland is the largest part of the Mid-Atlantic Ridge that rises above sea level, and its central volcanic plateau is erupting almost constantly. The interior consists of a plateau characterised by sand and lava fields, mountains, and glaciers, and many glacial rivers flow to the sea through the lowlands. Iceland is warmed by the Gulf Stream and has a temperate climate, despite a high latitude just outside the Arctic Circle. Its high latitude and marine influence keep summers chilly, and most of its islands have a polar climate.

Naval trawlers are vessels built along the lines of a fishing trawler but fitted out for naval purposes; they were widely used during the First and Second World Wars. Some—known in the Royal Navy as "Admiralty trawlers"— were purpose-built to naval specifications, others adapted from civilian use. Fishing trawlers were particularly suited for many naval requirements because they were robust vessels designed to work heavy trawls in all types of weather, and had large clear working decks. A minesweeper could be created by replacing the trawl with a mine sweep. Adding depth charge racks on the deck, ASDIC sonar below, and a 3-inch (76 mm) or 4-inch (102 mm) gun in the bow equipped the trawler for anti-submarine duties.

The Western Approaches is an approximately rectangular area of the Atlantic Ocean lying immediately to the west of Ireland and parts of Great Britain. Its north and south boundaries are defined by the corresponding extremities of Britain. The coast of the mainland forms the eastern side and the western boundary is the 30 degree meridian, which passes through Iceland. The area is particularly important to the United Kingdom, because many of its larger shipping ports lie within it.

Western Local Escort Force (WLEF) referred to the organization of anti-submarine escorts for World War II trade convoys from North American port cities to the Western Ocean Meeting Point near Newfoundland where ships of the Mid-Ocean Escort Force (MOEF) assumed responsibility for safely delivering the convoys to the British Isles.

Halifax Harbour is a large natural harbour on the Atlantic coast of Nova Scotia, Canada, located in the Halifax Regional Municipality. Halifax largely owes its existence to the harbour, being one of the largest and deepest ice-free natural harbours in the world. Before Confederation it was one of the most important commercial ports on the Atlantic seaboard. In 1917, it was the site of the world's largest man-made accidental explosion, when the SS Mont-Blanc blew up in the Halifax Explosion of December 6.

The Benson class was a class of destroyers of the U.S. Navy built 1939–1943. The thirty 1,620-ton Benson-class destroyers were built in two groups. The first six were authorized in fiscal year 1938 (FY38) and laid down at Bethlehem Steel, Quincy, Massachusetts, and three naval shipyards. The remaining 24 "repeat Bensons" were authorized in 1940–42 and built at four Bethlehem Steel yards. They were laid down after the first group was commissioned. These plus the "repeat Livermores" were also known at the time as the Bristol class. During World War II the Bensons were usually combined with the Livermores as the Benson-Livermore class; this persisted in references until at least the 1960s. In some references both classes are combined and called the Benson class. The Benson- and Gleaves-class destroyers were the backbone of the pre-war Neutrality Patrols and brought the action to the enemy by participating in every major campaign of the war.

The Clemson class was a series of 156 destroyers which served with the United States Navy from after World War I through World War II.

USS MacLeish (DD-220/AG-87) was a Clemson-class destroyer in the United States Navy during World War II. She was named for Lieutenant Kenneth MacLeish.

USS Niblack (DD-424), a Gleaves-class destroyer, is the only ship of the United States Navy to be named for Albert Parker Niblack. Niblack became the Director of Naval Intelligence 1 March 1919, and Naval Attache in London 6 August 1920. As vice admiral, he commanded U.S. Naval Forces in European waters from 15 January 1921 to 17 June 1922.

Aconit was one of the nine Flower-class corvettes lent by the Royal Navy to the Free French Naval Forces. During World War II, she escorted 116 convoys, spending 728 days at sea. She was awarded the Croix de la Libération and the Croix de Guerre 1939–1945, and was cited by the British Admiralty. Following the war she was used as whaling ship for three different companies from 1947 to 1964.

USS Gleaves (DD-423) was the lead ship of the Gleaves class of destroyers. She is the only ship of the United States Navy to be named for Admiral Albert Gleaves, who is credited with improving the accuracy and precision of torpedoes and other naval arms.

USCGC Spencer (WPG-36) was a Treasury-class cutter of the United States Coast Guard that served during World War II. She was named for U.S. Treasury Secretary John Canfield Spencer.

The Battle of the Coral Sea, from 4 to 8 May 1942, was a major naval battle between the Imperial Japanese Navy (IJN) and naval and air forces of the United States and Australia. Taking place in the Pacific Theatre of World War II, the battle is historically significant as the first naval action in which the opposing fleets neither sighted nor fired upon one another, attacking over the horizon with aircraft carriers instead.

A battleship is a large armored warship with a main battery consisting of large caliber guns. It dominated naval warfare in the late 19th and early 20th centuries.

USS Mississippi (BB-41/AG-128), the second of three members of the New Mexico class of battleship, was the third ship of the United States Navy named in honor of the 20th state. The ship was built at the Newport News Shipbuilding Company of Newport News, Virginia, from her keel laying in April 1915, her launching in January 1917, and her commissioning in December that year. She was armed with a battery of twelve 14-inch (356 mm) guns in four three-gun turrets, and was protected by heavy armor plate, with her main belt armor being 13.5 inches (343 mm) thick.

USS Idaho (BB-42), a New Mexico-class battleship, was the fourth ship of the United States Navy to be named for the 43rd state. She was the third of three ships of her class. Built by the New York Shipbuilding Corporation of Camden, New Jersey, she was launched in June 1917 and commissioned in March 1919. She was armed with a battery of twelve 14-inch (356 mm) guns in four three-gun turrets, and was protected by heavy armor plate, with her main belt armor being 13.5 inches (343 mm) thick.

An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a naval force to project air power worldwide without depending on local bases for staging aircraft operations. Carriers have evolved since their inception in the early twentieth century from wooden vessels used to deploy balloons to nuclear-powered warships that carry numerous fighters, strike aircraft, helicopters, and other types of aircraft. While heavier aircraft such as fixed-wing gunships and bombers have been launched from aircraft carriers, these aircraft have not landed on a carrier. By its diplomatic and tactical power, its mobility, its autonomy and the variety of its means, the aircraft carrier is often the centerpiece of modern combat fleets. Tactically or even strategically, it replaced the battleship in the role of flagship of a fleet. One of its great advantages is that, by sailing in international waters, it does not interfere with any territorial sovereignty and thus obviates the need for overflight authorizations from third-party countries, reduces the times and transit distances of aircraft and therefore significantly increase the time of availability on the combat zone.

USS Hornet (CV-8), the seventh U.S. Navy vessel of that name, was a Yorktown-class aircraft carrier of the United States Navy.

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.

Destroyer leader (DL) was the United States Navy designation for large destroyers from 9 February 1951 through the early years of the Cold War. United States ships with hull classification symbol DL were officially frigates from 1 January 1955 until 1975. The smaller destroyer leaders were reclassified as destroyers and the larger as cruisers by the United States Navy 1975 ship reclassification so destroyer escorts could be reclassified as frigates (FF) in conformance with international usage of the term.

The E and F-class destroyers were a group of 18 destroyers built for the Royal Navy during the 1930s. The ships were initially assigned to the Home Fleet, although they reinforced the Mediterranean Fleet during the Italian invasion of Abyssinia of 1935–36 and enforced the Non-Intervention Agreement during the Spanish Civil War of 1936–1939. After the beginning of the Second World War in August 1939, the E-class ships were mostly assigned to escort duties under the Western Approaches Command, while the Fs were assigned to escort the ships of the Home Fleet. Between them they sank four German submarines through March 1940 while losing only one ship to a submarine.

HMS Fame was an F-class destroyer built for the Royal Navy during the 1930s. Although assigned to the Home Fleet upon completion, the ship was attached to the Mediterranean Fleet in 1935–36 during the Abyssinia Crisis. During the Spanish Civil War of 1936–1939, she spent time in Spanish waters, enforcing the arms blockade imposed by Britain and France on both sides of the conflict. Fame served in the Norwegian Campaign in 1940 before she was severely damaged when she ran aground in October. The ship was refloated several months later and spent a year and a half under repair. Fame was converted into an escort destroyer while under repair and was assigned to escort duties in the North Atlantic when the repairs were completed in mid-1942.

HMS Firedrake was an F-class destroyer built for the Royal Navy during the early 1930s. Although assigned to the Home Fleet upon completion, the ship was attached to the Mediterranean Fleet in 1935–36 during the Abyssinia Crisis. During the Spanish Civil War of 1936–39, she spent much time in Spanish waters, enforcing the arms blockade imposed by Britain and France on both sides of the conflict.

The HX convoys were a series of North Atlantic convoys which ran during the Battle of the Atlantic in the Second World War. They were east-bound convoys and originated in Halifax, Nova Scotia from where they sailed to ports in the United Kingdom. They absorbed the BHX convoys from Bermuda en route. Later, after the United States entered the war, HX convoys began at New York.

USCGC Campbell (WPG-32) was a 327-foot (100 m) Secretary-class United States Coast Guard ship built at the Philadelphia Navy Yard in 1935-1936 and commissioned in 1936. Seven similar "combat cutters" were built and named for secretaries of the United States Treasury.

German submarine U-124 was a Type IXB U-boat of Nazi Germany's Kriegsmarine during World War II. She operated in the Atlantic as part of the 2nd U-boat flotilla, both west of Scotland and east of the eastern US coast. She was also present off northern South America.

German submarine U-617 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 31 May 1941 by Blohm & Voss in Hamburg as yard number 593, launched on 14 February 1942 and commissioned on 9 April under Kapitänleutnant Albrecht Brandi.

German submarine U-518 was a Type IXC U-boat of the Nazi Germany's Kriegsmarine during World War II. She saw considerable success from her launch on 11 February 1942 until she was sunk on 22 April 1945. The U-boat was laid down at the Deutsche Werft in Hamburg as yard number 314 on 12 June 1941, and commissioned on 25 April 1942 with Fregattenkapitän Hans-Günther Brachmann in command. He was replaced on 19 August 1942 by Kapitänleutnant Friedrich-Wilhelm Wissmann. She sank nine ships and damaged three more in seven active patrols. U-518 had a crew of 56, and was by then commanded by Oberleutnant zur See Hans-Werner Offermann from 13 January 1944.

Convoy ON 166 was the 166th of the numbered ON series of merchant ship convoys Outbound from the British Isles to North America. Sixty-three ships departed Liverpool 11 February 1943 and were met the following day by Mid-Ocean Escort Force Group A-3 consisting of the Treasury-class cutters Campbell and Spencer and the Flower-class corvettes Dianthus, Chilliwack, Rosthern, Trillium and Dauphin.

Convoy SC 121 was the 121st of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island to Liverpool. The ships departed New York City 23 February 1943; and were met by the Mid-Ocean Escort Force Group A-3 consisting of the United States Coast Guard (USCG) Treasury-class cutter USCGC Spencer, the American Wickes-class destroyer USS Greer, the British and Canadian Flower-class corvettes HMS Dianthus, HMCS Rosthern, HMCS Trillium and HMCS Dauphin and the convoy rescue ship Melrose Abbey. Three of the escorts had defective sonar and three had unserviceable radar.

HMS Borage was a Flower-class corvette that served in the Royal Navy during World War II.

HMS Meadowsweet was a Flower-class corvette that served with the Royal Navy during the Second World War. She served as an ocean escort in the Battle of the Atlantic.

HMS Watchman was a W-class destroyer of the British Royal Navy that saw service in the final months of World War I, in the Russian Civil War, and in World War II.

HMS Vanessa (D29) was a V-class destroyer of the British Royal Navy that was in service during World War I and World War II.

Convoy SC 118 was the 118th of the numbered series of World War II slow convoys of merchant ships from Sydney, Cape Breton Island, to Liverpool. The ships departed New York City on 24 January 1943 and were met by Mid-Ocean Escort Force Group B-2 consisting of V-class destroyers Vanessa and Vimy, the Treasury-class cutter Bibb, the Town-class destroyer Beverley, Flower-class corvettes Campanula, Mignonette, Abelia and Lobelia, and the convoy rescue ship Toward.

HMS Escapade was an E-class destroyer built for the Royal Navy in the early 1930s. Although assigned to the Home Fleet upon completion in 1934, the ship was attached to the Mediterranean Fleet in 1935–1936 during the Abyssinia Crisis. During the Spanish Civil War of 1936–1939 she spent considerable time in Spanish waters, enforcing the arms blockade imposed by Britain and France on both sides of the conflict. Escapade was assigned to convoy escort and anti-submarine patrol duties in the Western Approaches when World War II began in September 1939, but transferred back to the Home Fleet at the end of the year.

ORP Burza was a Wicher-class destroyer of the Polish Navy which saw action in World War II.

HMS Garland, also known by her Polish designation ORP Garland, was a G-class destroyer built for the Royal Navy in the mid-1930s. During the Spanish Civil War of 1936–1939 the ship spent considerable time in Spanish waters, enforcing the arms blockade imposed by Britain and France on both sides of the conflict. Shortly after World War II began, she was badly damaged by the premature explosion of her own depth charges and required over six months of repairs. Before these were completed, Garland was loaned to the Polish Navy in May 1940. The ship was assigned to the Mediterranean Fleet afterwards and escorted convoys there before being assigned to the Western Approaches Command in September for escort duties. She escorted a convoy from Gibraltar to Malta during Operation Halberd in September 1941 and escorted Convoy PQ 16 from Iceland to Murmansk in May 1942. She was badly damaged by a near miss from a German bomber during that operation and required three months of repairs.

HMS Orchis was a Flower-class corvette that served in the Royal Navy during World War II.

HMS Keppel was a Thornycroft type flotilla leader built for the Royal Navy at the end of the First World War. She was completed too late to serve in that conflict, but saw extensive service in the inter war years and in World War II. She was an effective convoy escort and U-boat killer, being credited with the destruction of five U-boats during the Battle of the Atlantic. She was the second of three ships named for 18th century Admiral Augustus Keppel.

HMS Abelia was a Flower-class corvette that served in the Royal Navy and was built by Harland and Wolff in 1941.

USS Branch (DD-197) was a Clemson-class destroyer in the United States Navy that entered service in 1920. After a short active life, Branch was placed in reserve in 1922. The ship was activated again for World War II before being transferred to the Royal Navy in 1940. Renamed HMS Beverley, the destroyer served in the Battle of the Atlantic as a convoy escort and was torpedoed and sunk on 11 April 1943.

German submarine U-176 was a Type IXC U-boat in Nazi Germany's Kriegsmarine during World War II.

Convoy SC 104 was the 104th of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island to Liverpool. During October 1942, a U-boat wolf pack sank eight ships from the convoy. The convoy escorts sank two of the attacking submarines.

Convoy ON 144 was a trade convoy of merchant ships during the Second World War. It was the 144th of the numbered series of ON convoys Outbound from the British Isles to North America. The ships departed Liverpool on 7 November 1942 and were joined on 8 November by Mid-Ocean Escort Force Group B-6 consisting of the Flower-class corvettes Vervain, Potentilla, Eglantine, Montbretia and Rose and the convoy rescue ship Perth. Group B-6 had sailed without the destroyers Fame and Viscount which had been damaged in the battle for eastbound convoy SC 104. The United States Coast Guard cutters Bibb, Duane, and Ingham accompanied the convoy from the Western Approaches with ships that detached for Iceland on 15 November.

German submarine U-524 was a Type IXC U-boat of Nazi Germany's Kriegsmarine during World War II.

HMS Alisma was a Flower-class corvette that served in the Royal Navy.

The C and D class was a group of 14 destroyers built for the Royal Navy in the early 1930s. As in previous years, it was originally intended to order a complete flotilla comprising eight destroyers—plus a flotilla leader as the ninth unit—in each year. However, only four ships—plus a leader—were ordered under the 1929–1930 Programme as the C class. The other four ships planned for the C class were never ordered as an economy measure and disarmament gesture by the Labour government of Ramsay MacDonald. A complete flotilla—the 'D' class—was ordered under the 1930–1931 Programme.

German submarine U-94 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. She was laid down on 9 September 1939 at the F. Krupp Germaniawerft in Kiel as yard number 599, launched on 12 June 1940 and commissioned on 10 August 1940 under Kapitänleutnant Herbert Kuppisch.

German submarine U-124 was a Type IXB U-boat of Nazi Germany's Kriegsmarine during World War II. She operated in the Atlantic as part of the 2nd U-boat flotilla, both west of Scotland and east of the eastern US coast. She was also present off northern South America.

Convoy SC 94 was the 94th of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island, Nova Scotia, to Liverpool. The ships departed Sydney on 31 July 1942 and were met by Mid-Ocean Escort Force Group C-1.

Convoy ON 154 - also ON(S) 154 or ONS 154 - was a North Atlantic convoy of the ON series which ran during the battle of the Atlantic in World War II. It was the 154th of the numbered series of merchant ship convoys Outbound from the British Isles to North America. It came under attack in December 1942 and lost 13 of its 50 freighters. One of the attacking U-boats was destroyed.

German submarine U-552 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 1 December 1939 at Blohm & Voss in Hamburg as yard number 528, launched on 14 September 1940, and went into service on 4 December 1940. U-552 was nicknamed the Roter Teufel after her mascot of a grinning devil, which was painted on the conning tower. She was one of the more successful of her class, operating for over three years of continual service and sinking or damaging 35 Allied ships with 164,276 GRT and 1,190 tons sunk and 26,910 GRT damaged. She was a member of 21 wolf packs.

German submarine U-132 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 10 August 1940 by Vegesacker Werft, Bremen-Vegesack as yard number 11, launched on 10 April 1941 and commissioned on 29 May that year under Kapitänleutnant Ernst Vogelsang.

German submarine U-552 was a Type VIIC U-boat built for Nazi Germany's Kriegsmarine for service during World War II. She was laid down on 1 December 1939 at Blohm & Voss in Hamburg as yard number 528, launched on 14 September 1940, and went into service on 4 December 1940. U-552 was nicknamed the Roter Teufel after her mascot of a grinning devil, which was painted on the conning tower. She was one of the more successful of her class, operating for over three years of continual service and sinking or damaging 35 Allied ships with 164,276 GRT and 1,190 tons sunk and 26,910 GRT damaged. She was a member of 21 wolf packs.

German submarine U-43 was a Type IXA U-boat of Nazi Germany's Kriegsmarine during World War II. The keel for U-43 was laid down in August 1938 at Bremen; she was launched in May 1939 and commissioned in August.

Convoy ON 127 was a trade convoy of merchant ships during the second World War. It was the 127th of the numbered series of ON convoys Outbound from the British Isles to North America and the only North Atlantic trade convoy of 1942 or 1943 where all U-boats deployed against the convoy launched torpedoes. The ships departed Liverpool on 4 September 1942 and were met at noon on 5 September by the Royal Canadian Navy Mid-Ocean Escort Force Group C-4 consisting of the Canadian River-class destroyer Ottawa and the Town-class destroyer St. Croix with the Flower-class corvettes Amherst, Arvida, Sherbrooke, and Celandine. St. Croix's commanding officer, acting Lieutenant Commander A. H. "Dobby" Dobson RCNR, was the senior officer of the escort group. The Canadian ships carried type 286 meter-wavelength radar but none of their sets were operational. Celandine carried Type 271 centimeter-wavelength radar. None of the ships carried HF/DF high-frequency direction finding sets.

Convoy SC 107 was the 107th of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island to Liverpool. The ships departed New York City on 24 October 1942 and were found and engaged by a wolfpack of U-boats which sank fifteen ships. It was the heaviest loss of ships from any trans-Atlantic convoy through the winter of 1942–43. The attack included one of the largest non-nuclear man-made explosions in history, when U-132 torpedoed ammunition ships SS Hobbema and SS Hatimura - both were sunk, one exploded, with the German submarine also being destroyed in the explosion.

USS Herndon (DD-198) was a Clemson-class destroyer in the United States Navy. Herndon served in the United States Coast Guard as CG-17. She was later transferred to the Royal Navy as HMS Churchill and still later to the Soviet Navy as Deyatelny.

HMS Buttercup was a Flower-class corvette built for the Royal Navy. She served during the Second World War first as part of the Royal Navy Section Belge (RNSB), and then later as part of the Royal Norwegian Navy. Between 1946 and 1957 she served as HNoMS Nordyn. The Norwegian government then sold her and she became the whaler Thoris until she was broken up in 1969.

HMS Swale (K217) was a River-class frigate of the Royal Navy (RN) from 1942 to 1955, loaned to the South African Navy for six months at the end of the Second World War.

Radar is a radiolocation system that uses radio waves to determine the distance (ranging), angle (azimuth), and radial velocity of objects relative to the site. It is used to detect and track aircraft, ships, spacecraft, guided missiles, and motor vehicles, and map weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the objects. Radio waves from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds.

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 Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models designated as various LB-30s, in the Land Bomber design category.