Spiegelberg mining interests dated from the early 1860s. In 1861 Soloman Jacob and Levi joined investors incorporating the Montezuma Copper Mining Company of Santa Fé, New Mexico, and Lehman served on the board of directors of the Willison Silver Mining Company in 1872. Lehman's acquisition of the San Marcos Pueblo grant may have been stimulated by his interest in copper mining. During the Civil War, Levi, while en route to Chihuahua with a wagon train of merchandise, was captured by General Henry Hopkins Sibley's Confederate forces near Socorro, within days following the Battle of Valverde. He was charged with being a Union spy, but was recognized by a former Secretary of the Territory of New Mexico, Colonel A. M. Jackson, and released. The brothers suffered heavy mercantile business losses during this New Mexico Campaign of 1862, especially in Albuquerque. However, they still managed to prosper through their government contracts, insurance and mining investments, and their Santa Fe banking and exchange house. The Spiegelbergs were appointed sutlers to the New Mexico Volunteers between July 1861 and July 1864. Flora Spiegelberg recalled that during the occupation of Santa Fe, more than fifty thousand dollars in merchandise passed from the Spiegelbergs into Confederate hands. Until 1870, large merchants filled the role of the non-existent banks of New Mexico. Large purchases often involved the use of property as security, in essence, mortgage banking. The Spiegelbergs issued their own highly respected company scrip as substitutes for legal tender in 1863, when the territorial legislative assembly granted a provisional charter to create the Bank of New Mexico, but failed to gain congressional approval. Levi Spiegelberg was among the ten prominent New Mexicans seeking that charter. In 1870, the First National Bank of New Mexico received a charter under Lucien Maxwell in Santa Fe, which was taken over within months by Thomas B. Catron, one of the largest individual landholders in U.S. history, with Stephen Benton Elkins and others. The Spiegelbergs quickly formed the Second National Bank of New Mexico in 1872, with principal (and majority interest holding) stockholders, Lehman and Willie in Santa Fe, and Solomon and Levi, in New York. The wealth of the Spiegelbergs may be compared to other prominent New Mexicans of the time. That reported by Ceran St. Vrain in 1860 was $200,000; the Dold brothers of Las Vegas, $76,500 each; Solomon Spiegelberg, $65,000.