[9] Henry de Mille, whose ancestors were of English and Dutch-Belgian descent, was a North Carolina-born dramatist, actor, and lay reader in the Episcopal Church.

[11] He worked as a playwright, administrator, and faculty member during the early years of the American Academy of Dramatic Arts, established in New York City in 1884.

[21] John Philip Sousa was a friend of the family, and DeMille recalled throwing mud balls in the air so neighbor Annie Oakley could practice her shooting.

[55] In the spring of 1913, DeMille found success producing Reckless Age by Lee Wilson, a play about a high-society girl wrongly accused of manslaughter, starring Frederick Burton and Sydney Shields.

[63] When William found out that DeMille had begun working in the motion picture industry, he wrote his brother a letter, saying that he was disappointed that Cecil was willing "to throw away [his] future" when he was "born and raised in the finest traditions of the theater".

After the film was shown, viewers complained that the shadows and lighting prevented the audience from seeing the actors' full faces and said they would pay only half price.

Additionally, during the war, DeMille volunteered for the Justice Department's Intelligence Office, investigating friends, neighbors, and others he came in contact with in connection with the Famous Players–Lasky.

The Roaring Twenties were the boom years and DeMille took full advantage, opening the Mercury Aviation Company, one of America's first commercial airlines.

[117] When "talking pictures" were invented in 1928, DeMille made a successful transition, offering his own innovations to the painful process; he devised a microphone boom and a soundproof camera blimp.

The Union Pacific gave DeMille access to historical data, early period trains, and expert crews, adding to the film's authenticity.

[140] DeMille was anti-communist and abandoned a project in 1940 to film Ernest Hemingway's For Whom the Bell Tolls due to its communist themes, even though he had already paid $100,000 for the rights to the novel.

[146] After working on it, DeMille was the master of ceremonies at a rally organized by David O. Selznick in the Los Angeles Coliseum in support of the Dewey–Bricker presidential ticket as well as Governor Earl Warren of California.

[164] On November 7, 1954, while in Egypt filming the Exodus sequence for The Ten Commandments, DeMille (who was 73) climbed a 107-foot (33 m) ladder to the top of the set and had a serious heart attack.

[167][note 11] Due to his frequent heart attacks, DeMille asked his son-in-law, actor Anthony Quinn, to direct a remake of his 1938 film The Buccaneer.

[193] DeMille had large and frequent office conferences to discuss and examine all aspects of the working film including story-boards, props, and special effects.

[196] DeMille was adept at directing "thousands of extras",[114] and many of his pictures include spectacular set pieces: the toppling of the pagan temple in Samson and Delilah;[197] train wrecks in The Road to Yesterday,[198] Union Pacific[199] and The Greatest Show on Earth;[200] the destruction of an airship in Madam Satan;[201] and the parting of the Red Sea in both versions of The Ten Commandments.

In addition to his use of volatile and abrupt film editing, his lighting and composition were innovative for the time period as filmmakers were primarily concerned with a clear, realistic image.

[213] Paulette Goddard's refusal to risk personal injury in a scene involving fire in Unconquered cost her DeMille's favor and a role in The Greatest Show on Earth.

[208] DeMille made stars of unknown actors: Gloria Swanson, Bebe Daniels, Rod La Rocque, William Boyd, Claudette Colbert, and Charlton Heston.

[219][220] DeMille cast some of his performers repeatedly, including Henry Wilcoxon,[221] Julia Faye, Joseph Schildkraut,[222] Ian Keith,[223] Charles Bickford,[224] Theodore Roberts, Akim Tamiroff,[225] and William Boyd.

[229] DeMille was often criticized for making his spectacles too colorful and for being too occupied with entertaining the audience rather than accessing the artistic and auteur possibilities that film could provide.

[232] DeMille's distinctive style can be seen through camera and lighting effects as early as The Squaw Man with the use of daydream images; moonlight and sunset on a mountain; and side-lighting through a tent flap.

[234] DeMille's 1956 version of The Ten Commandments, according to director Martin Scorsese, is renowned for its level of production and the care and detail that went into creating the film.

[243] Another common theme in DeMille's films is the reversal of fortune and the portrayal of the rich and the poor, including the war of the classes and man versus society conflicts such as in The Golden Chance and The Cheat.

DeMille's highest-grossing films include: The Sign of the Cross (1932), Unconquered (1947), Samson and Delilah (1949), The Greatest Show on Earth (1952), and The Ten Commandments (1956).

[257] Meanwhile, Sumiko Higashi sees DeMille as "not only a figure who was shaped and influenced by the forces of his era but as a filmmaker who left his own signature on the culture industry.

Martin Scorsese cited Unconquered, Samson and Delilah, and The Greatest Show on Earth as DeMille films that have imparted lasting memories on him.

[304] In 1957, DeMille gave the commencement address for the graduation ceremony of Brigham Young University, wherein he received an honorary Doctorate of Letter degree.

[308] In the same ceremony, DeMille received a nomination from Directors Guild of America Award for Outstanding Directorial Achievement in Motion Pictures for The Greatest Show on Earth.

[110] Six of DeMille's films — The Arab, The Wild Goose Chase, The Dream Girl, The Devil-Stone, We Can't Have Everything, and The Squaw Man (1918) — were destroyed by nitrate decomposition, and are considered lost.