Williams Pass, California.
Williams Pass is a mountain pass in the northern Sierra Nevada mountains. It is best known as the site of two battles in the Rocky Mountain War between the United States of Mexico and the Confederation of North America in the early 1850s.
A North American force numbering between 80,000 and 100,000 led by General David Homer passed westward through Williams Pass in June 1850 en route to California. After being repulsed by General Francisco Hernandez's California Guard at the Battle of San Fernando on 5-7 July 1850, Homer's North Americans retreated back to Williams Pass. There they found the eastern end of the pass blocked by a second Mexican army led by General Michael Doheny. Unable to dislodge Doheny's Mexicans, and with Hernandez's Californians occupying the western end of Williams Pass, Homer found himself trapped in the pass with winter approaching.
Governor-General Henry Gilpin, having learned of the trap that had been set for Homer's men, sent a second army of Southern Confederation militia troops under General FitzJohn Smithers to relieve Homer's men. However, Smithers was delayed in setting out, and he did not reach the eastern end of Williams Pass until mid-November 1850, by which time the winter snows had begun to fall within the pass. Smithers' men attacked Doheny's army from the east, trapping them in the pass with Homer's men, before being trapped themselves by the snow. All four armies had become trapped, and the Battle of Williams Pass was fought over the course of five months in the midst of ferocious winter weather.
By the time the spring thaw came to Williams pass in late March 1851, only 31,000 Mexicans out of an original force of 97,000 were still alive, while the North Americans had lost 113,000 out of 140,000 men. Gilpin dismissed the terrible losses suffered by the C.N.A., insisting "Our nation can afford to lose men' the Mexicans cannot. We shall grind them to dust."
Gilpin sent a third North American army led by General Herkimer Ware to try to force its way through Williams Pass, but Ware's force was plagued with desertions and mutinies. In the Second Battle of Williams Pass, Ware's army was defeated by Mexican armies led by Colonel Miguel Fernandez and Chief Brave Eagle. The Second Battle of Williams Pass was the last major conflict of the Rocky Mountain War before Gilpin's fall from power in February 1853.
Williams Pass does not have an entry in Sobel's index. It is mentioned on pages 129-131 and 137 of For Want of a Nail ....