Over footage depicting a covered wagon party, a narrator recalls that in 1846, the Mormon Battalion--a band of five hundred men accompanied by a small group of women and children--undertook a 2,000-mile trek in the cause of California's independence. As the narrator quotes from the Gettysburg Address, the scene shifts to present day San Diego, California, where a bus caravan is arriving for a celebration of the Mormon Battalion. The narrator explains that in 1846, after Mexican forces attacked American pioneers near the Rio Grande, President James K. Polk ordered General Zachary Taylor to invade northern Mexico. California looked to Mormon leader Brigham Young for assistance, and Young promptly helped assemble a volunteer company. Judge Advocate P. LeRoy Nelson, one of the Sons of the Utah Pioneers, describes the journey, which ended in San Diego, as "the longest march of infantry ever recorded in the annals of mankind." A reenactment of the Battalion's call to action at Council Bluffs, Iowa, is presented. Nelson remarks that when the Battalion was called up, Mormons were being persecuted and exiled, denied "every right in the Constitution." Young promised his followers that not one of them would fall to enemy fire, and none of them did. The March to California began 16 Jul 1846, and the Battalion members demonstrated great courage in the face of bad weather and brutal conditions. The film then returns to San Diego, where men and women in period costumes walk down the center of the street with a covered wagon. The festivities resume as Earl J. Slade, mayor of Salt Lake City, introduces members of the Sons of the Utah Pioneers. The celebration then moves to Presidio Park, where Marines raise the flag and speeches are given by historian Leo J. Muir, Fred E. H. Curtis, church president George Albert Smith and other Mormon leaders. California Governor Earl Warren welcomes the marchers, and Los Angeles Mayor Fletcher Bowron accepts a key to Salt Lake City. After the program ends, the narrator recalls that the Mormon Battalion was under military orders for five and a half months. When their service was completed, one hundred men reenlisted, and the rest began the trek back to their families in Utah and Iowa. The narrator says that the Battalion established the course for subsequent migration, adding that the Santa Fe and Southern Pacific Railroads now use the routes the Battalion took. The caravan then moves to San Bernardino, where Mormon Day is celebrated.
Although the viewed print was only 25 minutes long, a negative print of the film at the UCLA Film and Television Archive confirms that the film was feature length. Credits were taken from a trailer for the film contained in the Archive. Although the credits indicate that Edward Finney Productions copyrighted the film in 1950, the title was not found in copyright records. The film opens with the following onscreen credit: "Edward Finney presents official pictures of the Sons of the Utah Pioneers trek commemorating The Mormon Battalion." The credits also include the following written prologue: "Dedicated to Brigham Young and the Mormon Pioneer Fathers, five hundred strong, who with a handful of women and children, covered 2,000 miles in 1846 in one of the greatest infantry marches in history. They joined the 'Army of the West' to help California in its fight for freedom." According to a May 29, 1950 Hollywood Reporter news item, The Mormon Battalion had its premiere in Salt Lake City, UT in mid-1950, and was scheduled to play at the Mission in San Diego, CA after that.