In 1939, Germany won the “Battle of Poland.”  In early 1940 Germany won the “Battle of France.”[1]  A German invasion of Britain required control of the air over the English Channel.  The British won the “Battle of Britain.”[2]  Then began the “Battle of the Atlantic.”  Britain imported much of its food and raw materials; it would have to send forces to its far-flung battle fronts by sea; no Britain as a base, no cross-Channel attack in 1944 or any other year.  To stay in the war, Britain had to control the shipping lanes of the world.  Hitler ordered his navy to strangle Britain through submarine warfare.  The critical phase of the “Battle of the Atlantic” ran from 1940 to 1943.  All the while, Britain’s survival hung by a thread.[3] 

  At first, the Royal Navy had only the help of the small navies of the Commonwealth countries and a few Polish and Free French ships.  After Pearl Harbor, the United States Navy joined the fight.  “Greyhound” (dir. Aaron Schneider, 2020) provides an absorbing account of the problems of convoy escorts during the critical stage of the “Battle of the Atlantic.”[4]  The movie tracks a 37-ship convoy bound for Britain.[5]  What do we learn? 

First, on either end of the voyage, the convoy is also protected by aircraft, armed with depth charges and searching a much greater area than can the escort vessels.  In between is the “Mid-Atlantic Gap” when the convoy is out of range of air cover.[6]  Then the convoy has only the escort vessels.  The German U-boats loved this “Black Hole.”

Second, modern science helped arm the escort vessels.  “High Frequency Direction Finding” (HFDF or “Huff-Duff”) could locate the source of the long-distance radio messages used by the U-boats to communicate with their bases.  ASDIC (now called Sonar for Sound Navigation and Ranging) allowed the escort vessels to locate U-boats at closer range.  Attacks on submarines used depth charges whose water-pressure sensitive triggers caused them to explode at pre-set depths. 

Third, the U-boats still had advantages.  On the one hand, ASDIC could tell location, but not depth and depth charges had to explode within 20 feet to damage a submarine; when on the surface they had a high speed through the water and a very low silhouette that made them hard to see.  Surface night attacks were common.  Get a ship burning and it illuminated other targets.  On the other hand, the Germans subs took up a picket line across likely convoy routes, then converged on sighted convoys to attack in “wolf packs” that could swarm the escort vessels. 

Fourth, Captain Ernest Krause (Tom Hanks), the commander of the U.S.S. “Keeling,” represents the whole US war-effort in the early period after Pearl Harbor.  The Americans would exert an ever-increasing weight in the Anglo-American alliance as time went by, but the British had been at war for two years already.  Krause relies on his long years of service in a highly-trained and unforgiving Navy and upon an imposing personal sense of duty to cross his own “mid-Atlantic gap.” 

Fifth, words like “success” and “victory” had only a relative meaning.  Six of the merchant ships and one of the escort vessels are sunk by the Germans, and the “Keeling” is damaged.  Still, 31 merchantmen and three escorts survive.  It was a “tonnage war” and much more got through than was lost.  As Krause, exhausted by 52 straight hours on the bridge managing the complex battle trudges toward his cabin, he hears the crews of the merchant ships cheering. 

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[1] An umbrella term for conquering Denmark, Norway, the Netherlands, Belgium, and France, and driving the British Expeditionary force off the Continent at Dunkirk.  

[2] See “The Battle of Britain” (dir. Guy Hamilton, 1969).  It is historically accurate and the flying scenes are thrilling.  Based on Derek Wood and Derek Dempster, The Narrow Margin.  The Battle Of Britain (1969) (youtube.com) 

[3] There are a host of good books on this subject, but one might start with Samuel Eliot Morison, The Battle of the Atlantic, September 1939—May 1943 (1947), a volume in Professor/Admiral Morison’s Official History of U.S. Naval Operations in World War II.  Morison knew the sea and how to write readable history. 

[4] Other Good-to-Great movies on this subject include: “San Demetrio London” (dir. Charles Frend, 1943); “The Enemy Below” (dir. Dick Powell, 1957) The Enemy Below 1957 (youtube.com); “The Cruel Sea” (dir. Charles Frend, 1953); and, from the German side, “Das Boot” (dir. Wolfgang Peterson, 1981).   There’s a documentary as well: “U-Boats vs. Allies” U-Boats vs Allies – WWII: Witness to War – S01 EP3 – History Documentary (youtube.com) 

[5] East-bound convoys had an “HX” designation (originally for leaving Halifax, Nova Scotia). 

[6] Both the RAF and the USAAF prioritized strategic bombing of Germany in allocating long-range aircraft, stinting convoy protection.  Eire remained resolutely neutral and denied Britain the use of ports and airfields in Western Ireland that would have greatly eased the situation.  Had Britain fallen to Hitler,…