The archive describes Pershing at the head of troops under the flag, with ghostly knights and red-cross shields in the sky behind him.
Who made it and why
FRAME: Committee on Public Information, Division of Films, lithograph associated with H.C. Miner, 1918. Library of Congress, LC-USZC4-1539. Public domain, published before 1931. The poster says the picture is official, under government auspices, shot by Signal Corps and Navy photographers. That disclosure is unusually complete. The title does the rest of the work.
What it got right or wrong
Right: there was a film, it was the government's, and Pershing commanded the expeditionary force. Wrong: the knights. Nothing in a Signal Corps camera makes 1918 a crusade. A crusade is a war preached as God's. The United States had not declared one. Wilson had asked Congress, on 2 April 1917, to make the world "safe for democracy" and said "we desire no conquest, no dominion." A sky full of cross-bearing ghosts pulls the other direction. It transfers a religious war's prestige onto a republic's army. The footage did not need that, which is why the title is doing something the footage could not.
The constitutional and liberty angle
An official film is government speech. It may persuade. It may not, consistent with a free constitution, become the only picture of the war the public is allowed to see. This poster does not impose that monopoly. It does show the temptation: call the war holy, and dissent starts to look like sacrilege. The Sedition Act was available for people who would not clap. The knights are the soft version of the same demand. A citizen can honor the soldiers in the photograph and refuse the halo painted over them.
Its legacy
"Crusade" stayed in American political talk long after the armistice, usually as a compliment. On this sheet it is a specific borrow, and it is visible. The honest lines are the dull ones: official, Committee on Public Information, Signal Corps. Start there. The ghosts are the part that wants to skip the hearing.
Sources
FRAME object record, "Pershing's Crusaders," 1918. CPI Division of Films. Library of Congress, LC-USZC4-1539.
Woodrow Wilson, address to Congress, 2 April 1917, in War and Peace, ed. Baker and Dodd, vol. 1 (1927), p. 14, as quoted on the FRAME Wilson administration page.