Jim Harrison's novella Legends of the Fall, made famous by the 1994 film starring Brad Pitt and Anthony Hopkins, recounts the tragedies that ensue when the three sons of an aristocratic Montana rancher ride north in 1914 to enlist in the Canadian Expeditionary Force. Given that an estimated 17 percent of Montana's young men volunteered or were conscripted to fight in the bloody trenches of France and Belgium during World War I, Harrison drew from the real history of a young state that was largely enthusiastic about that war.

Such ardor can, however, have a darker side. In 1918, Montana passed the nation's harshest sedition law, which criminalized criticism of the war effort and served as a model for the federal government's own Sedition Act enacted a few months later. Although the war was nearly over when it was passed, 200 Montanans, many of them German immigrants beset by a nationwide anti-German hysteria, were charged and 79 were convicted for being vocal in their opposition to the war.

Walking through a new exhibition at the de Young Museum in San Francisco entitled Weapons of Mass Seduction, one gets more insight into how such fanaticism was whipped up. Drawn from the extensive collection of the Achenbach Foundation for Graphic Arts of the San Francisco Fine Arts Museums, the exhibition chronicles martial propaganda from countries on both sides of the two world wars. Visitors see French recruiting posters, German calls to arms, and copies of sheet music for cheery Great War ditties meant to be sung by family and friends around the American parlor piano. Posters, films, leaflets, and other items in this well-curated exhibition highlight the ways in which tools being developed by burgeoning advertising and entertainment industries were pressed into service to shape public sentiment and gin up popular enthusiasm.

The iconic Army recruiting image of a finger-pointing Uncle Sam saying "I Want YOU" greets the visitor entering the gallery. Recruitment, however, plays a surprisingly small role in the exhibition, perhaps because of the dominant role that conscription played in both world wars. The Uncle Sam poster made its recruiting debut in 1917, the same year that the draft was instituted.