The screenplay by Coward was inspired by the exploits of Captain Lord Louis Mountbatten, who was in command of the destroyer HMS Kelly when it was sunk during the Battle of Crete.
Coward composed the film's music as well as starring in the film as the ship's captain. The film also starred John Mills, Bernard Miles, Celia Johnson and Richard Attenborough in his first screen role.
The film opens with the narration: "This is the story of a ship" and the images of shipbuilding in a British dockyard. The action then moves forward in time showing the ship, HMS Torrin, engaging German transports in a night-time engagement during the Battle of Crete in 1941. However, when dawn breaks, the destroyer comes under aerial attack from German bombers.
Eventually the destroyer receives a critical hit following a low-level pass. The crew abandon ship as it rapidly capsizes. Some of the officers and ratings manage to find a Carley float as the survivors are intermittently strafed by passing German planes. From here, the story is told in flashback using the memories of the men on the float. The first person to reveal his thoughts is Captain Kinross (Coward), who recalls the summer of 1939 when the Royal Naval destroyer HMS Torrin is being rushed into commission as the possibility of war becomes a near certainty.
The ship spends a relatively quiet Christmas in the north of Scotland during the Phoney War. But by 1940, the Torrin is taking part in a naval battle off the coast of Norway. During the action, a young terrified sailor (Attenborough) leaves his station while another rating (Mills) returns to work his gun after its crew is knocked unconscious by a torpedo strike. The damaged Torrin is towed back to port, all the time being harried by dive-bombers.
Safely back in harbour, Captain Kinross tells the assembled ship's company that during the battle nearly all the crew performed as he would expect; however one man didn't. But he tells everyone present they may be surprised to know that he let him off with a caution as he feels as Captain he failed to make them understand their duty.
Returning to the present, the float survivors watch the capsized Torrin take on water as the badly damaged ship slowly sinks. The raft is again strafed by German planes. Some men are killed, and "Shorty" Blake (Mills) is wounded. This leads to a flashback in which Blake remembers how he met his wife-to-be, Freda, on a train while on leave. It is also revealed, she is related to the Torrin's affable Chief Petty Officer Hardy (Miles). When both men return to sea, Freda moves in with CPO Hardy's wife and mother-in-law.
The Torrin participates in the Dunkirk evacuation of the British Expeditionary Force, (portrayed in the film by the 5th Battalion of the Coldstream Guards). Meanwhile, the nightly Blitz takes its toll on British towns. Blake soon gets a letter from home to say that Freda has given birth to his son during one raid. But the letter also says that Hardy's wife and mother-in-law were killed in the same attack. Stoically he goes to the Petty Officers' Mess to tell Hardy (who is in the process of writing a letter home) the bad news.
The flashback ends as the survivors on the life raft watch the capsized Torrin finally sink. Captain Kinross leads a final "three cheers" for the Torrin when suddenly another passing German plane rakes the raft with machine gun fire, killing and wounding more men. A British destroyer soon appears and begins rescuing the men. On board, Captain Kinross talks to the survivors and collects addresses from the dying. He tells the young man who once deserted his post that he will write and tell his parents that they can be proud that he did his duty; the critically injured young man smiles and dies peacefully. Relatives soon receive telegrams informing them about the fate of their loved ones.
Captain Kinross and the 90 surviving members of the crew are taken to Alexandria in Egypt. Wearing a mixture of odd clothing and standing in a military depot, Captain Kinross tells them that although they lost their ship and many friends, who now "lie together in fifteen-hundred fathoms", he notes that these losses should inspire them to fight even harder in the battles to come. The ship's company is then told they are to be broken up and sent as replacements to other ships that have lost men. Captain Kinross then shakes hands with all the ratings as they leave the depot. When the last man goes, the emotionally tired captain turns to his remaining officers, silently acknowledges them before walking away.
An epilogue then concludes: bigger and stronger ships are being launched to avenge the Torrin; Britain is an island nation with a proud, indefatigable people; Captain Kinross is now in command of a battleship. Its massive main guns fire against the enemy.
Shortly after his play Blithe Spirit opened in the West End in July 1941, Noël Coward was approached by Anthony Havelock-Allan, who was working with the production company Two Cities Films. Its founder, Filippo Del Giudice, was interested in making a propaganda film and wanted someone well known to write the screenplay.
Coward agreed to work on the project as long as the subject was the Royal Navy and he was given complete control.
As the sinking of HMS Kelly on 23 May 1941 was still on Coward's mind, he decided to use the ship's demise as the basis for his script. Mountbatten, aware that there was some public antipathy to his political ambitions, agreed to support the project as long as it was not a conspicuous biography of his own experiences. In order to do research, Coward visited the naval base in Plymouth, where Michael Redgrave, with whom he was involved in a relationship at the time, was stationed. He also visited Portsmouth and the Home Fleet at Scapa Flow, where he sailed on HMS Nigeria.
Coward spent the final months of 1941 drafting a screenplay. However, when he submitted it to Havelock-Allan, the producer told him the film would run between eight and nine hours if it was made as written because it included lengthy scenes in Paris, China and the West Indies. Havelock-Allan told Coward he needed to trim the plot down to the basics by eliminating everything that was not related to the Torrin or its crew. Heeding the advice, Coward started his story with the laying of the ship's keel in 1939 and concluded it soon after it sinks off the coast of Crete. For the speech at the end of the film, when Capt. Kinross addresses the survivors from the Torrin in Alexandria, Coward used the real speech that Mountbatten gave to the surviving crew of HMS Kelly after they were rescued and taken to Egypt.
Coward was determined to portray Captain Kinross in the film, despite the studio's concern that his public "dressing gown and cigarette-holder" persona might make it difficult for audiences to accept him in the role of a tough navy man. Havelock-Allan supported him, although he later called his performance "always interesting, if not quite convincing." Coward also needed to convince the censors that the sinking of the ship was a crucial scene and not the threat to public morale they perceived it to be.
Coward had experience directing plays, but he was a novice when it came to films, and he knew he needed to surround himself with professionals if the project was to succeed. He had seen and admired Ronald Neame's work, and he hired him as cinematographer and chief lighting technician. Knowing he could handle the direction of the actors but would be at a loss with the action scenes, he asked David Lean to supervise the filming of those. In Which We Serve proved to be the first of several films on which the two would collaborate.
Shooting began at Denham Studios on 5 February 1942. From the start Coward was happy to let production crew members take charge in their individual areas of expertise, while he concentrated on directing the actors and creating his own portrayal of Kinross. But he soon became bored with the mechanics of filmmaking and after six weeks he came to the studio only when scenes in which he appeared were being filmed. At one point he invited the royal family to the set and newsreel footage of their visit proved to be good publicity for the film.
During the filming, the character of Albert Fosdike, "Shorty" Blake's brother-in-law, was recast after actor William Hartnell turned up late for his first day of shooting. Coward berated Hartnell in front of cast and crew for his unprofessionalism. He then made him personally apologise to everyone before sacking him. Michael Anderson, the film's first-assistant director took over the part (credited as "Mickey Anderson").
Coward was anxious that it succeed, not only because it was his first film project, but because he felt it was his contribution to the war effort and he wanted it to be perceived as such by the public. The première was a gala event held as a benefit for several naval charities and Coward was pleased to see a large presence of military personnel.
Interiors were filmed at Denham Studios, in Denham, Buckinghamshire. The Kinross family picnic scene, set during the Battle of Britain in 1940, was filmed on location on the Dunstable Downs in Bedfordshire.
Although the film makers took great care to conceal locations because of wartime censorship, scenes were shot at Plymouth's naval dockyard in Devon and the naval station on the Isle of Portland. For example, the departure of Blake and Hardy was filmed in front of Devonport's original main entrance, the Keyham Dock Gate. Smeaton's Tower on the seafront at Plymouth Hoe was used for the leave ashore scenes between "Shorty" Blake (Mills) and his wife Freda (Kay Walsh).
The destroyer HMAS Nepal played HMS Torrin.
The film was the second most popular movie at the British box office in 1943.
The film was one of the most successful British films ever released in the US, earning $1.8 million in rentals.
Bosley Crowther of The New York Times observed, "There have been other pictures which have vividly and movingly conveyed in terms of human emotion the cruel realities of this present war. None has yet done it so sharply and so truly as In Which We Serve... For the great thing which Mr. Coward has accomplished in this film is a full and complete expression of national fortitude ... Yes, this is truly a picture in which the British may take a wholesome pride and we may regard as an excellent expression of British strength."
Variety called the film "a grim tale sincerely picturized and splendidly acted throughout" and added, "Only one important factor calls for criticism. It is that all the details are too prolonged. The author-producer-scriptwriter-composer and co-director gives a fine performance as the captain of the vessel, but acting honors also go to the entire company. Stark realism is the keynote of the writing and depiction, with no glossing of the sacrifices constantly being made by the sailors."
Despite largely positive reviews by audiences and critics alike, the film was not well received by some within the Admiralty who dubbed it "In Which We Sink".
On Christmas Eve 1942 in New York, the National Board of Review of Motion Pictures honoured the film as the Best English Language Film of the Year citing Bernard Miles and John Mills for their performances.
The film was nominated in the 1943 Academy Awards for Best Picture and Best Original Screenplay (losing out to Casablanca and Princess O'Rourke respectively). However Coward was presented with an Academy Honorary Award for "his outstanding production achievement."
In Which We Serve also won the New York Film Critics Circle Award for Best Film (beating Casablanca) and the Argentine Film Critics Association Award for Best Foreign Film in 1943.
A Region 2 DVD with a running time of 96 minutes was released by Carlton on 11 October 1999. A Region 1 DVD was released as part of the David Lean Collection by MGM on 7 September 2004. It features subtitles in English, Spanish and French and an English audio track in Dolby Digital 1.0. In March 2012, The Criterion Collection released "In Which We Serve" on Blu-ray and DVD as part of the "David Lean Directs Noel Coward" Box Set, which includes a short documentary on the making of In Which We Serve.