Sibley was initially successful at the Battle of Valverde on 20–21 February and pressed on to capture Albuquerque and Santa Fe in the first weeks of March. Although the subsequent Battle of Glorieta Pass on March 28 ended in an apparent Confederate victory on the field, Sibley had to retreat because his supply train was destroyed and most of the horses and mules killed or driven off during the fight. At the same time, Union forces were approaching New Mexico from the west, the California Column. Glorieta Pass has been called the "Gettysburg of the West" by some authors; Sibley's retreat to the campaign's starting point at Fort Bliss in April ended the hopes of the Confederate nation to stretch to the Pacific Ocean and use the mineral wealth of California and possibly Colorado.