The Pacific coast theater of the American Civil War consists of major military operations in the United States on the Pacific Ocean and in the states and Territories west of the Continental Divide. The theater was encompassed by the Department of the Pacific that included the states of California, Oregon, and Nevada, the territories of Washington, Utah, and later Idaho.The Bear River Massacre was formally in Washington Territory, which was partitioned into the Idaho Territory subsequent to the battle. However, Col. Connor had the Bear River valley reassigned to his military District of Utah prior to his campaign to protect a settlement of Mormons there.
The operations of Union volunteer troop detachments, primarily from California, some from Oregon, and a few companies from Washington Territory, were directed mostly against Indigenous Americans in the theater. Union and Confederate regular forces did not meet directly within the Pacific Department except in New Mexico Territory. Operations were directed against Confederate irregulars in California and strong garrisons were placed in Southern California and southern New Mexico Territory to control the region which had strong secessionist sympathies.
Confederate States Navy warships operated in the Pacific Ocean, but the naval operations did not succeed in interrupting commerce to the Eastern United States. The last of these commerce raiders, CSS Shenandoah, fired the last shot of the war in the Bering Sea off the coast of Alaska. Attempts by the Confederacy to buy or seize ships for commerce raiding on the West Coast were thwarted by alert Union officials and the Pacific Squadron.
Secession crisis on the West Coast During the secession crisis following Lincoln's election as President of the United States in 1860, a group of Southern sympathizers in California made plans to secede with Oregon to form a "Pacific Republic". Their plans rested on the cooperation of Colonel (Brevet Brigadier General) Albert Sidney Johnston, headquartered in Benicia, California, who commanded all the Federal troops of the Department of the Pacific. Johnston met with some of these Southern men, but before they could propose anything to him he told them that he had heard rumors of an attempt to seize the San Francisco forts and arsenal at Benicia, that he had prepared for that, and would defend the facilities under his command with all his resources and to the last drop of his blood. He told them to tell this to their friends.Asbury Harpending, The great diamond hoax: and other stirring incidents in the life of Asbury Harpending, San Francisco, James H. Barry Co., 1913.p.36 Deprived of his aid, the plans for California and Oregon to secede from the United States never came to fruition. Meanwhile, Union men feared Johnston would aid such a plot and telegraphed Washington asking for his replacement. Brig. Gen. Edwin Vose Sumner was soon sent west via Panama to replace Johnston in March 1861. Johnston resigned his commission on 9 April, and after Sumner arrived on 25 April, Johnston turned over his command and moved with his family to Los Angeles.
On 28 March 1861, the newly formed Arizona Territory voted to separate from New Mexico Territory and join the Confederacy. This increased Union officials' fears of a secessionist movement to separate Southern California from the rest of California and join the Confederacy. This fear was based on the demonstrated Southern Californian desire for separation from the rest of California in the overwhelming vote for the 1859 Pico Act, the strength of secessionists in the area, and their declared intentions and activities, especially in forming militia companies.
Operations against secessionists and the Confederacy
Outbreak of the Civil War
Securing Southern California At the outbreak of the Civil War, the secession of Southern California seemed possible. The populace was largely in favor of separation from California, militias with secessionist sympathies had been formed, and Bear Flags, the banner of the Bear Flag Revolt, had been flown for several months by secessionists in Los Angeles and San Bernardino counties. After word of the Battle of Fort Sumter reached California, there were public demonstrations by secessionists. Only San Diego had a small Union garrison. However, when three companies of Federal cavalry were moved from Fort Mojave and Fort Tejon into Camp Fitzgerald, in Los Angeles, in May–June 1861, secession quickly became impossible.
Suspected by local Union authorities, General Johnston evaded arrest and joined the secessionist militia company, the Los Angeles Mounted Rifles as a private, leaving Warner's Ranch on 27 May in their journey across the southwestern deserts to Texas, crossing the Colorado River into the Confederate Territory of Arizona, on 4 July. A. J. King, Undersheriff of Los Angeles County, and other influential men in El Monte, California, that had formed another secessionist militia on 23 March, the Monte Mounted Rifles, were thwarted in their plans to assist Johnston when Undersheriff King ran afoul of Federal authorities and when army officers at San Pedro held up a shipment of arms from John G. Downey, the Governor of California, preventing the activation of the Rifles.J. M. Scammel, Military Units in Southern California, 1853-1862; California Historical Quarterly, Vol. XXIV, Chapter 3. II The Los Angeles Units, p.14
Charged with all the supervision of Los Angeles, San Bernardino, San Diego, and Santa Barbara counties, on 16 August Major William Scott Ketchum steamed from San Francisco to San Pedro and made a rapid march to encamp near San Bernardino on 26 August, and with Companies D and G of the 4th Infantry Regiment later reinforced at the beginning of September by a detachment of 90 First U.S. Dragoons and a howitzer. Except for frequent sniping at his camp, Ketchum's garrison stifled any secessionist uprising from Belleville, California and a show of force by the Dragoons in the streets of San Bernardino at the end of election day quelled a secessionist political demonstration during the September gubernatorial elections in San Bernardino County.The California State Military Museum, Historic California Posts:Posts at San BernardinoThe War of the Rebellion SERIES I, Volume L, Chapter LXII - Operations on the Pacific Coast, Part I, pp.16,27,28,429,450,466,512,515,567,569,585,594,595,601-602,606,607,612,614-615,617,660-661,663,669-670,687 Union commanders would rely on the San Bernardino Mounted Rifles and Captain Clarence E. Bennett for intelligence and help in holding the pro-Southern San Bernardino County for the Union in late 1861 as Federal troops were being withdrawn and replaced by California Volunteers.California State Militia and National Guard Unit Histories, San Bernardino Rangers. This history was written in 1940 by the Works Progress Administration (WPA) in conjunction with the Office of the Adjutant General and the California State Library
On 25 September, the District of Southern California was established, with its first headquarters at Camp Latham, west of Los Angeles; this was later moved to Drum Barracks.The California State Military Museum, Historic California Posts: Camp Latham Historic California Posts: Drum Barracks (Camp San Pedro, Camp Drum, Fort Drum, and Wilmington Depot)Historic California Posts: Fort MacArthur - Military Museum This District was first formed to control the secessionist majority population in Southern California. This district included Tulare County to the north, which at the time was much larger than it is now, including all of what is now Kings, Kern, and Inyo counties and part of Fresno County. From Camp Latham, Ketchum's regular soldiers were relieved on October 20 by three companies of the 1st California Cavalry sent out to San Bernardino County and establish Camp Carleton and later Camp Morris.The California State Military Museum, Historic California Posts: Camp Carleton (Camp Banning, Camp Prentiss, New Camp Carleton)The California State Military Museum, Historic California Posts: Camp Morris Volunteer troops were also sent to Camp Wright in San Diego County to watch the southern overland approach to California across the Colorado Desert from Fort Yuma, located on the west bank of the Colorado River. They were also to intercept secessionist sympathizers traveling to the east to join the Confederate Army.
In March 1862, all the troops drilling at Camp Latham were transferred to Camp Drum, leaving a company of soldiers to observe the Los Angeles area. Following flooding at Camp Carleton in the Great Flood of 1862, the garrison moved to New Camp Carleton, near the secessionist hotbed of El Monte. For the rest of the Civil War, Union garrisons were maintained in Southern California.
Campaign of the California Column
In early 1862, the District headquarters was used as the base for the campaign of the California Column into Confederate Arizona. California sent some of their Volunteer Regiments east to clear the Confederate garrisons from southern New Mexico Territory and West Texas around El Paso. Subsequently, California units remained there as garrisons fighting the Navajo, the Comanche, and the Apache until after the Civil War when they were relieved by Federal Troops in 1866. In March 1865, Arizona Territory, under the military-controlled District of Arizona, was transferred from the Department of New Mexico to the Department of the Pacific and in July 1865 to the Department of California.
Pacific Squadron operations Because of the blockade of the Confederacy, the Union Navy could not spare many ships to guard the ports and shipping of the Pacific Coast and the Pacific Squadron remained small. One ship was always on station at Panama City to protect that Pacific Terminal of the gold shipments carried by the vessels of the Pacific Mail. The remaining ships patrolled the coast between Panama and British Columbia as needed. Mare Island Naval Shipyard in San Francisco Bay was the Squadron's permanent base.
Pacific coastal defenses To protect Union-controlled ports, especially San Francisco Bay, the shipping point of gold and silver from the Pacific Coast, from possible attacks by Confederate commerce raiders, several forts were either built or improved upon. Coastal fortifications at Fort Point and Camp Sumner were built at the edge of the Presidio, as well as at Fort Baker on the Marin Headlands.The California State Military Museum, Historic California Posts: Camp Sumner One Civil War-era fort, Post of Alcatraz Island or Fort Alcatraz, on a rocky island just inside the Golden Gate, served as a prison for secessionists and later became the infamous Federal penitentiary, Alcatraz. San Francisco Bay was also protected by the Benicia Arsenal, Fort Mason at San Francisco's Point San Jose, and Camp Reynolds on Angel Island.
At the mouth of the Columbia River, two forts were established. In 1862, a camp called Post at Cape Disappointment (later Fort Cape Disappointment) was established in Washington Territory. Fortifications were built and artillery installed to cover the mouth of the river. In 1863, Fort at Point Adams (later Fort Stevens) was established in Oregon on the south bank at the mouth of the Columbia River to do the same function as Fort Cape Disappointment. Posts also existed or were established at the ports of San Diego, San Pedro Bay, Santa Barbara, Noyo, Humboldt Bay in California and Fort Vancouver in what's now Washington state. In 1864, Santa Catalina Island was seized by Federal forces, a post established and garrisoned, and the population removed to prevent it being used as a base for privateers. For a time Federal authorities considered making it a reservation location for Indians captured in the Bald Hills War, but this never came to pass.
Naval incidents