Prior to writing the novellete that would become the basis for Lifeboat, John Steinbeck wrote The Moon is Down, his first novel about the war.  Like Lifeboat, it is a heavily allegorical story that, although unrealistic to a modern audience, was well reviewed and liked by the World War II-era American public who "wanted not art but propaganda."

Lifeboat partially originated as a project that the Merchant Marines asked Hollywood to produce in order to create public awareness of the threat U-boats presented its ships.  Steinbeck's original version of the story was much truer to the Marines wishes, and much less of an allegory than the final film ended up being.  While the characters were meant to represent a microcosm of American society, the element of a disorganized Democracy set against the strong-wlled Nazi was not present.  In contrast, the self-made man shows the leadership qualities that must have been used to amass his fortunes, not the facistman who finds it so easily to give up power.  Also, the Nazi is a weak individual who after only one act of deception is killed.  The focus of the book is not the Nazi's ascension to control but of what life as a Merchant Marine and the experience of being shelled and stranded is like.

After Steinbeck completed his work on the project, three additional drafts were done, and by the end the story only vaguely represented the original.  MacKinlay Kantor's draft was thrown out early on by Hitchcock, though he is credited with increasing the allegory's prominence in the story.  One of Frank Capra's collaborators Jo Swerling stripped away a lot of the realism of the characters and provided the "Capra-corn" melodramatic elements.  Hitchcock, the master of details, rewrote the final draft shortly before shooting to "give it narrative form."

After seeing his original vision transformed so much, Steinbeck eventually wrote and asked to have his name taken off of the film, claiming that he wanted no part in something that so clearly "damaged the war effort."  Most of all, as revealed in a personal letter, it seems as if Steinbeck hated the transformation of the working class characters from ones with dignity to stereotypes, criticizing Hithcock's "middle-class" sensibilities.

In the midst of Hollywood's war time effort, incorporating pro-American propaganda into its films, it's somewhat ironic to see the process converting a film with origins in propaganda transformed by the process into what many reviewers of the time considered to be anti-American.