In 1942, in the face of Nazi aggression in Libya, American tank commander Sergeant  Joe Gunn and his men, "Waco" Hoyt, Fred Clarkson and Jimmy Doyle, are ordered to retreat.  Surrounded by German troops to the north, east and west, their only viable route lies through the desert to the south.  Boarding their damaged tank, the Lulubelle, the Americans head into the parched sands.  There they meet a group of Allied stragglers, including Captain Jason Halliday, a member of the British medical corps whose hospital and patients have been wiped out by the Germans; British soldiers Ozzie Bates and Marty Williams; Peter Stegman, a South African serving in the British military, and Jean Leroux, a French soldier.

Knowing that the tank offers their only salvation, Gunn invites the men aboard, even though water supplies are severely limited.  As they proceed across the desert, they see Tambul, a British Sudanese solider, and his Italian prisoner, Giuseppe.  After Tambul, who is familiar with the desert, tells them about an old caravan trail leading to a well, Gunn appoints him guide and welcomes him aboard the Lulubelle.  Realizing that he will perish if left behind, Giuseppe begs Gunn for passage, but the American refuses and drives off.  Taking pity on Giuseppe, who stumbles along in the tracks of the tank, Gunn relents and allows him onboard.

Soon after, they are attacked by a German bomber.  Luring the aircraft to a lower altitude, the Lulubelle blasts it out of the sky, sending its pilot, Captain Von Schletow, crashing to the ground.  After taking Von Schletow prisoner, the troops of the Lulubelle continue on, even though Clarkson has been severely wounded in the attack.  Upon arriving at the well, they discover that it is dry.  More bad news follows when Clarkson dies of his wounds and the order comes over the radio to regroup and defend the threatened cities of Cairo and Alexandria.  Hampered by a sputtering engine and blinding sandstorm, the tank limps toward the ruins of Fort Bir Acroma, the site of the next well.  That well is also dry, except for a trickle of water dripping from some underground rocks.  Tambu climbs down the well and carefully collects the drops of precious liquid, hoping to gather sufficient resources to continue.  Meanwhile, a platoon of Germans, also in search of water, are told by their Arab guide about the well at Bir Acroma.

Dispatched by the Germans, a scouting party of two soldiers approaches the ruins, and is captured by Gunn and his men.  Gunn bribes one of them with water to reveal the position of the German battalion, and learning that the battalion is five hundred strong, the sergeant proposes that his ragtag force try to delay the Germans until the Allies can regroup.  Gunn puts his proposal to a vote and, despite Williams' skepticism, the men choose to risk their lives and fight.  To lure the Germans to Bir Acroma, Gunn tells his captives that he will swap food for water and then sends them back on foot to their troops to relay his offer.  While Gunn and the others await the enemy, Waco drives the German jeep to the Allied outpost for reinforcements.

That night, the German forces swarm over the hills surrounding Bir Acroma.  After Stegman is killed in the attack, Von Falken, the German commander, offers to let Gunn and his men go free in exchange for their weapons.  Gunn counters with an offer of water for German weapons, and when Von Falken declines, the fighting continues.  As the ragtag army think that they are seeing Waco approach the outpost, Waco's truck overheats, leaving him stranded.  Swigging the last of the water, Waco starts out on foot.

Meanwhile, at the fort, night falls and the Germans attack, killing Williams.  Von Schletow then tries to enlist Giuseppe in a scheme to inform the Germans that there is no water.  When Giuseppe refuses to cooperate and denounces Hitler, Von Schletow stabs him and escapes.  Near death, Giuseppe staggers out to the front line to warn Gunn of the German's treachery.  Before Von Schletow is able to expose Gunn's plot, Tambul runs after him and strangles him, and in turn is killed by Nazi bullets.  The next day, Von Falken calls another meeting.  Representing Gunn, Leroux meets with the German, and after reiterating the terms of guns for water, turns to walk back toward camp and is shot in the back by a Nazi bullet.

Now nearly out of ammunition, Halliday speculates that only a miracle can save them.  After a German bullet wounds Jimmy, Halliday pulls him into the ruins for shelter and the two perish when a German shell levels the building.  Meanwhile, Waco, exhausted and near death, claws his way up a sand dune and is found by a British patrol.  Back at the camp, Gunn and Ozzie, the last two survivors, await death as the Germans attack.  When Gunn answers them with gunfire, the Germans, defeated by thirst, offer their guns for water.  Halliday's miracle occurs when Gunn discovers that the shelling has opened up the well.  After ordering the Germans to disarm for a drink of water, Gunn and Ozzie take them prisoner and begin to herd them through the desert, where they are met by Waco and a platoon of British tanks.  When Waco greets Gunn with the news that the British have held the Germans back at El Alimin, Gunn realizes that their sacrifice has not been for naught.

Notes
The working title of this film was Somewhere in Sahara.  Onscreen credits note that this picture was based on an incident in the Soviet photoplay The Thirteen.  That film, released as Trinadstat in Russia, was a 1937 Amkino Soviet production directed by Mikhail Romm.  The opening credits dedicate the film to "the IV Armored Corps of the Army Ground Forces, whose cooperation made it possible to tell this story."  The opening credits also include the following prologue:  "In June 1942, a small detachment of American tanks with American crews joined the British Eighth Army in North Africa to get experience in desert warfare under actual battle conditions.  History has proved that they learned their lesson well..."  Although the character played by Louis Mercier is named "Jean Leroux" in the CBCS and in reviews, his dog tags bear the name of "Pierre Leroux."

HR news items yield the following information about this film's production:  In November 1942, it was announced that the film was to star Glenn Ford and Melvyn Douglas and that Bernard Nedell was testing for a top role.  Although a November 18, 1942 HR news item notes that Brian Aherne was to be in the cast, this reference might have been a typographical error for Brian Donlevy.  A mid-January 1943 news item adds that Humphrey Bogart was replacing Brian Donlevy, who was tired of appearing in war films.  Donlevy then took over the role Bogart was to have played in the Columbia comedy Once Upon a Time.  An HR production chart places Lewis Wilson, Jess Barker, and William Carter in the cast, but their participation in the released film has not been confirmed.

Desert scenes were shot on location at Brawley, the Imperial Valley, and Chatsworth, California, and Yuma, Arizona, according to HR news items.  Makeup artist Henry Pringle created the effect of facial perspiration by coating the actors' faces with Vaseline and then spraying them with water, according to a Look article.  A news item in NYT adds that 2,000 tons of sand were hauled onto the set to create the effect of loose sand.  The effect of ripples and swirls was created by spraying the sand with a film of light paint and then blowing it with a wind machine.  Shadows were spray-painted on the hills to make them stand out more clearly, according to the NYT article.  The film had its premiere at Camp Campbell, Kentucky, as part of a program celebrating the first anniversary of the activation of the IV Armored Corps, according to a news item in HR .  J. Carroll Naish was nominated for an Academy Award for Best Supporting Actor for his performance in this film.  The picture was also nominated for Best Cinematography and Best Sound Recording.  The 1952 Columbia western Last of the Comanches, starring Broderick Crawford, Barbara Hale, and Lloyd Bridges and directed by Andre de Toth, was loosely based on Sahara.