Book excerpt: In 1846-1847, a ragtag army of 800 American volunteers marched 3,500 miles across deserts and mountains, through Indian territory and into Mexico. There they handed the Mexican army one of its most demoralizing defeats and helped the United States win its first foreign war. Their leader Colonel Alexander Doniphan, also a volunteer, was a "natural soldier" of towering stature who became a national hero in the wake of his wartime exploits. Doniphan was a small-town Missouri lawyer untrained in military matters when he answered President Polk's call for volunteers in the war with Mexico. Working from a host of primary sources, Joseph Dawson focuses on Doniphan's extraordinary leadership and chronicles how the colonel and his 1st Missouri Mounted Regiment helped capture New Mexico and went on to invade Chihuahua. Contending with wildfires, sandstorms, poor provisions, and the threat of attack from Apaches, they eventually came face-to-face with the formidable cannon and cavalry of a much larger Mexican force. Yet, at the Battle of Sacramento, these hardy volunteers outflanked General Jose Heredia's army and claimed a stunning American victory on foreign soil. Dawson explores and analyzes the many facets of Doniphan's exploits, from the decision to proceed to Chihuahua in the wake of the Taos Revolt to the tactics that shaped his victory at Sacramento, describing that battle in heart-stopping detail. He tells how Doniphan's legal expertise enabled him to supervise America's first military government administering a conquered land at Santa Fe and highlights Doniphan's remarkable cooperation with U.S. Army officers at a time when antagonism typified relationships between volunteers and regulars. He also introduces readers to other key personalities of the campaign, from fellow officers Stephen W. Kearny and Meriwether L. Clark to James Kiker, the controversial scout whom Doniphan reluctantly trusted. Dawson's thorough account captures the expansionist mood of America in the mid-nineteenth century and helps us understand how American soldiers were motivated by the idea of Manifest Destiny. His portrait of Doniphan and his troops reinforces the importance of the citizen-soldier in American history and provides a new window on the war that changed forever the hopes and dreams of our border nations.