Between 1865 and 1887, the Great Plains experienced a dramatic faunal change as the vast buffalo herds were eliminated and millions of Texas cattle moved north onto the open ranges of Colorado, Wyoming, the Dakotas and Montana. Ranchers rarely bothered to acquire legal title to grazing lands; they simply “squatted” on what was still largely the public domain, creating a unique cattle kingdom. Eventually, the lure of immense cattle profits led to overcrowding and overgrazing, the problem exacerbated by the arrival of sheepherders and homesteaders to the region in the 1880s. As competition for grasslands increased, bitter range wars broke out between sheepherders and cattlemen in Colorado, Wyoming and elsewhere. And violence also erupted between cattlemen and farms, notably in the 1892 Johnson County Cattle War in Wyoming. But nature played the biggest role in bringing the open range cattle era to an end. A summer drought in 1886 was followed by the worst winter on record when blizzards, icy winds and unusually bitter cold blasted through the northern ranges. Millions of cattle, stranded in the snow, unable to paw down to the grass beneath, starved or froze to death. The ranchers who stayed in business after the so-called “Great Die-Up” learned to confine their herds to manageable fenced-in areas equipped with sufficient feed, water and shelter to sustain them year-round.

The Mexican War of 1846-1848 broke out ostensibly over a dispute about the Texan boundary. But it really originated in the expansionist spirit of “manifest destiny,” of which President James K. Polk was a leading proponent. Polk came to office determined to acquire the Mexican provinces of California and New Mexico and when Mexico refused to sell them, used a border clash as a pretext for war. Although American opinion was deeply divided over the conflict, the war turned out to be a succession of triumphs for American arms. The two provinces Polk coveted were easily overrun: General Zachary Taylor overwhelmed a much larger Mexican army at Buena Vista (February 1847); and General Winfield Scott’s seaborne expedition to Vera Cruz fought its way into the heart of Mexico against superior forces and captured Mexico City (September 1847), forcing Mexico to make peace. By the Treaty of Guadalupe-Hidalgo (February 1848), Mexico ceded the territories of California and New Mexico and acknowledged the Rio Grande as the Texas boundary. While the war brought the U.S. vast territorial gains — extending America’s western boundary to the Pacific — it also revived the simmering conflict over slavery and its extension to new territories.

Known as “the cradle of Texas liberty,” the Alamo in San Antonio was originally a Franciscan mission, later a fort. It was seized by Texan revolutionaries in 1835 when rebellion broke out against the Mexican dictator, General Antonio Lopez de Santa Anna. When the Alamo was besieged by Santa Anna’s army of 6,000 in February, 1836, it was defended by only about 180 men, poorly armed and supplied. but although ordered by Gen. Sam Houston, head of the Texan army, to destroy and abandon the fort, Col. William B. Travis and his co-commander, Col. James Bowie — reputedly the inventor of the “Bowie knife” — defied Santa Anna’s demands for surrender and prepared for defense. For ten days the Texans repelled successive assaults and even when the walls were finally breached, continued to fight in hand-to-hand combat until the end. Among the slain defenders was Col. Davy Crockett, the “coonskin Congressman” from Tennessee. The garrison’s heroic defense, together with news of the massacre of the Texan defenders of nearby Goliad after they had surrendered, stiffened Texan resistance. In April, 1836, with the rallying cry, “Remember the Alamo,” Houston’s small army defeated the Mexicans at the battle of San Jacinto, capturing Santa Anna and forcing him to sign treaties recognizing Texan independence. The Republic of Texas soon secured U.S. recognition, and in 1845, became the nation’s 28th state.