This film's plot device of two enemy commanders who grew to respect one another in battle and realize only war prevented a friendship between them was also shared by the first season "Star Trek" episode "Balance of Terror". An episode of "Voyage to the Bottom of the Sea", that also starred David Hedison, entitled "Killers of the Deep" also shared this theme and included stock footage from this movie.
In an interview in July 1977 with 'The New York Times', German actor Curd Jürgens who played the German submarine commander Captain Von Stolberg in this movie said: "This was an important picture for me because it was the first film after the war in which a German officer was not interpreted as a freak."
The American ship used in this movie was a Destroyer Escort by the name 'USS Whitehurst' (DE 634). My father was in the Navy at that time, and he helped paint over the 634 so the new number could be added. FYI, the 'USS Whitehurst' was sunk as a target for a new torpedo on 28 April 1971.
The U-Boat seen in this movie is far roomier and spacious, clean and tidy than the real German U-boats of World War II (which were more realistically depicted in the later movie, Das Boot (1981)). During the Second World War, these u-boats did not have passageways and private rooms and were dirty and cramped.
Two endings were shot: In one, both commanders die; in the other, a third vessel rescues them. The final ending was determined by preview results. The 'USS Haynes' was portrayed by the 'USS Whitehurst', captained by Walter R. Smith, who received a "technical advisor" credit and can be seen portraying the ship's chief engineer. Eva Novak can be seen in a photo as the wife of Von Stolberg.
This movie represents one of a select group of a few World War II submarine movies which have won the one single Academy Award in a technical category, that's just only the one Oscar in either special effects or sound editing. These movies include Crash Dive (1943); The Enemy Below (1957); Torpedo Run (1958) and U-571 (2000). The non-WW II sub-movie, The Hunt for Red October (1990) also won just the one Oscar as did the WW 2 part sub-movie 49th Parallel (1941), but for Best Original Story.
The destroyer escort 'USS Haynes' in this movie was played by the real 'USS Whitehurst' (DE-634). The cast spent about a month filming on board this vessel. Many of the crew of the 'USS Whitehurst' appeared in this movie. 20th Century-Fox production notes for this movie from the AMPAS Library declare that the 'USS Whitehurst' was a battle-hardened veteran from the Second World War which had during World War II been stationed at Pearl Harbor, Hawaii.
The tune sung by the U-Boat crew between the one-per-hour depth charge attacks, after the scene with the panicking torpedo man and the wrench, is from an 18th century march called "Der Dessauer Marsch". As a more popular song, it's also known by the first line of lyrics: "So leben wir" (translation: "That's how we live").
This picture marks the feature film movie debuts for David Hedison (as Al Hedison); Dan Tana and Ted Perritt, the latter of whom was a former messenger boy at the 20th century-Fox studio, playing a messenger.
The vessel the 'USS Whitehurst' was used in this movie and its captain, Lieutenant Commander Walter R. Smith USN acted as a technical advisor to the film production. Twentieth Century-Fox studio publicity stated that Smith played a role as this ship's Chief Engineer in the movie. Smith is not credited as such nor for any role and CBCS Credits state that Robert Boon portrayed a Chief Engineer in this movie. Apparently, Smith is the character who can be seen in the movie reading the comic 'Little Orphan Annie'.
The finale rescue was shot on location in the sea at Long Beach, California and on the ship the 'USS Alfred E. Cunningham' (DD-752), an Allen M. Sumner-class destroyer. Other location filming sites included the Pacific Ocean near Oahu, Hawaii for scenes on the 'USS Whitehurst' portraying the 'USS Haynes'.
Some of D.A. Rayner's wartime submarine adventures and experiences which appeared in his 'The Enemy Below' source novel to this movie and were adapted into this picture's story as well can be researched in Rayner's other book, 'Escort: the Battle of the Atlantic', particularly the 11 November 1944 Southern Ireland encounter between U-1200 and Allied corvettes (See pp. 224-228).
Eva Novak: As the wife of the German submarine commander, Von Stolberg (Curd Jürgens). Though Novak neither appears in the live-action of the movie itself nor is listed in this movie's cast credits, Novak is seen in a photograph appearing as Mrs Stolberg.
The trivia items below may give away important plot points.
According to the Australian DVD sleeve notes, "Producer-Director Dick Powell let the public decide the ending for The Enemy Below (1957). He filmed the movie with two endings, then let a preview audience vote for the ending they liked best. The ending he used won by unanimous vote." The ending which wasn't used had both submarine commanders, Captain Murrell (Robert Mitchum) and Von Stolberg (Curd Jürgens) die by drowning at the end of this picture when Murrell dives into the sea to rescue Von Stolberg. The used ending was the happy ending which had both of them rescued by a ship. Details of the two endings were reported in a July 1957 edition of 'The Hollywood Reporter' which stated that Powell filmed the two endings because he thought that the original ending (the unused one) was too bleak.
Though the Enemy Below is a story about a single destroyer against a U Boat in the history of World War Two naval warfare there was never a battle between a single destroyer against a submarine for a long period of time.