7th Regiment California Volunteer Infantry The 7th Regiment California Volunteer Infantry was an infantry regiment in the Union Army during the American Civil War . It spent its entire term of service in the western United States , attached to the Department of the Pacific , serving in California and Arizona Territory . They were known as the " Gold Diggers " in reference to the large number of recruits from the California ' s " Mother Lode " region . Later , they were also called the " Hungry Seventh " for the privations they suffered in Arizona , particularly at Fort Mason . The Regiment included many veterans of the Mexican – American War . Regimental Flag . While the Regiment was being organized and trained at the Presidio of San Francisco , Jonathan D . Stevenson presented them with the regimental flag of the unit he commanded in the Mexican - American War : The 7th New York Volunteers . The Regiment continued to carry this flag throughout its service , and it flew over Fort Mason during their time there . Service At Tubac and Fort Mason . In the Spring of 1865 , the Regimental Headquarters and Companies D , E , and G were assigned to Tubac , Arizona Territory . Though they were there primarily to operate against the Apaches , they were also assigned the job of reinforcing the International Line against potential incursions by the forces of the Mexican Empire and its French allies . As part of the ongoing war of the French Intervention , Imperialist forces had made recent advances into the neighboring Mexican State of Sonora , causing considerable alarm among officials in the United States . In September , the garrison was moved south to Calabazas , a small settlement near the border where they established a post called Fort Mason . They were joined there by the 1st Battalion of Native Cavalry , California Volunteers . Shortly afterward , Sonora Governor Ignacio Pesqueira , who had fled northward after his army had been destroyed in a series of battles with the Imperialists , arrived at the post with a small party seeking refuge . Colonel Lewis put the post , his officers , and his men at the Governor ' s disposal . Service at Fort Mason was generally considered miserable . Because of its somewhat swampy ( by Arizona standards ) location on the banks of the Santa Cruz River , the men suffered from an epidemic which at one point rendered over half of them too sick for duty and led to at least 25 deaths . The post suffered from supply problems as well . These conditions caused construction of permanent buildings at the post to slow to a halt , leaving the men to live in tents and temporary brush shelters during their service there and generally curtailing operations against the Apaches . Participation in one campaign against the Apaches , for instance , was aborted by a lack of adequate shoes . Despite this , the Seventh was , from time to time , able to put small expeditions into the field . On one such occasion , Captain Hiram A . Messenger led a scouting party of 15 men into the Huachuca Mountains in July , 1865 . The detachment found itself surrounded and under attack by a reported 100 or 200 Apaches and escaped after a fortuitous rainstorm ended a fight that lasted over an hour and left two soldiers dead and one wounded . The Regiment was ordered back to The Presidio in March , 1866 and was mustered out the following April and May .