Zoltan Korda was on of the premier directors in his day. "Sahara" is not your typical war movie, especially for one made during the war.
Like all good war movies, it conveys courage and sacrifice. Bogart is outstanding as the hard bitten tank commander on the run and cut off from his unit. Along the way he picks up several allied stragglers too.
One of those picked up is J Carroll Naish, an Italian soldier that Bogart could not conscientiously leave to die in the Sahara. Naish would go on to be nominated for a Best Supporting Actor Oscar.
They stumble upon a well, with little water. They are forced to defend this unyielding well from an element of Rommel's Afrika Corps, bluffing all the way. The defenders are represented by American,British,French and a Sudanese soldier played by Rex Ingram. Ingram was one of the few African American actors of the era who actually got some good roles. Notably, he was the genie in 1940's classic, "The Thief of Bagdad".
A highly underrated film, much better to the objective eye than a mere wartime programmer.