Originally classified restricted and bearing a title marked “Secret”, this film was made in 1944 just after the D-Day Invasion. Presumably, it was made as an indoctrination film for those combat engineers who would be participating in any seaborne invasion of the Japanese Mainland. This film tells the story of how the approximately 10,000 Seabees of Naval Construction Regiment 25 installed an artificial harbor and pontoon causeways on the beaches of Normandy. One of the largest engineering feats of the European campaign, the artificial harbor allowed tons of equipment and supplies to be landed rapidly, and helped ensure that the Allied beachhead in Normandy would grow. The effort was not without its share of disaster, as the film shows a large storm in the English Channel nearly crippled the newly-installed harbor.