Eighty years ago, in February 1917, the last of the U.S. troops serving in the Mexican Punitive Expedition recrossed the border from Palomas, Chihuahua, Mexico, into Columbus, New Mexico. Eleven months earlier the bandit Francisco "Pancho" Villa had raided Columbus. With approximately 485 men, known as Villistas, Villa had attacked the border town on March 9, 1916. According to War Department reports, ten American officers and soldiers were killed, two officers and five soldiers wounded, eight civilians killed, and two wounded. The Mexican irregulars' losses numbered approximately one hundred killed, with seven wounded and captured.1 From March 16, 1916, to February 14, 1917, an expeditionary force of more than fourteen thousand regular army troops under the command of Brig. Gen. John J. "Black Jack" Pershing operated in northern Mexico "in pursuit of Villa with the single objective of capturing him and putting a stop to his forays."2 Another 140,000 regular army and National Guard troops patrolled the vast border between Mexico and the United States to discourage further raids.3 The expedition generated a vast array of military records that are now held in the National Archives and Records Administration, resources that are underused and are of value to genealogists and historians. This article is divided into two installments and examines the conflict and the records. The first part describes the events preceding the Mexican Punitive Expedition. The second part will trace the campaign in Mexico and discuss some of the records created by the United States armed forces during its activities in Mexico and along the border in Arizona, New Mexico, and Texas.4