In the war declared against Mexico in 1846, volunteer troops from the South and West were essential. Jacob Robinson, mainly out of boredom and curiosity, came to Missouri from New Hampshire to enlist with Colonel Doniphan's expedition to Santa Fe and Chihuahua. Although the small army of less than 1,000 men consisted mostly of volunteers with little or no military experience, they ended up playing an extremely important role in American history. It was largely because of Doniphan's conquests that the United States was able to claim New Mexico, Arizona, and California.Robinson made a perfect observer for this campaign. Since he was originally from the East, he was much less judgmental than a Westerner would have been, looking upon the Mexicans and Navahos and the landscape with fresh and interested eyes. While the military significance of Robinson's journal is indisputable, he was often more captivated by the scenes and people he encountered than by their war with the Mexicans: "The journalist...is an observer of nature, and although engaged in some daring adventures, looks with more satisfaction upon the scenery of the new country through which he passes, than upon the exploits of the battle-field." Much of the campaign Robinson spent interacting with people rather than fighting them, and he was a very good observer."Here is one of the most singular marks of civilization ever seen among the Indians. Across the ravine is built a dam of rock 150 feet long, and 50 feet high; this stops the water from the mountains in the rainy season, and forms a lake six or eight miles in circuit, where otherwise there would be a dry plain. in the dry season they let the water out as they need it upon their lands, and thus raise good crops, and support two thousand inhabitants with large flocks..."Despite the somewhat romantic impressions Robinson conveys throughout much of the journal, the journey was difficult:"This is certainly a badly managed campaign. No medicines and no wagons are provided for the sick: we have to jumble them over the rocks and mountains, in our broken wagons, among the camp kettles and pork barrels. A poor chance is this when one is sick; what can he expect but to die?"A Journal of the Santa Fe Expedition Under Colonel Doniphan is a valuable work, as a first-hand account of a lesser-known war, and as an astute record of the conditions and ways of life in Old Santa Fe, the Navaho country, and Chihuahua.