United States Department of the Navy in the context of "United States Department of War"

The United States Department of Defense (DoD), also referred to as the Department of War (DoW), is an executive department of the U.S. federal government charged with coordinating and supervising the U.S. Armed Forces—the Army, Navy, Marines, Air Force, Space Force, and, for some purposes, the Coast Guard—and related functions and agencies. Headquartered at the Pentagon in Arlington County, Virginia, just outside Washington, D.C., the stated mission of the Department of Defense is "to provide the military forces needed to deter war and ensure our nation's security".

The Department of Defense is headed by the secretary of defense, a cabinet-level head who reports directly to the president of the United States. The president is commander-in-chief of the U.S. armed forces. Beneath the Department of Defense are three subordinate military departments: the Department of the Army, the Department of the Navy, and the Department of the Air Force. In addition, four national intelligence services are subordinate to the Department of Defense: the Defense Intelligence Agency, National Security Agency (NSA), National Geospatial-Intelligence Agency, and National Reconnaissance Office.

The United States Marine Corps (USMC), also referred to as the United States Marines or simply the Marines, is the maritime land force service branch of the United States Armed Forces. It is responsible for conducting expeditionary and amphibious operations through combined arms, implementing its own infantry, artillery, aerial, and special operations forces. The U.S. Marine Corps is a part of the United States Department of Defense and is one of the six armed forces of the United States and one of the eight uniformed services of the United States.

The Marine Corps has been part of the United States Department of the Navy since 30 June 1834 with its sister service, the United States Navy. The USMC operates installations on land and aboard sea-going amphibious warfare ships around the world. Additionally, several of the Marines' tactical aviation squadrons, primarily Marine Fighter Attack squadrons, are also embedded in Navy carrier air wings and operate from the aircraft carriers.

A naval base, navy base, or military port is a military base, where warships and naval ships are docked when they have no mission at sea or need to restock. Ships may also undergo repairs. Some naval bases are temporary homes to aircraft that usually stay on ships but are undergoing maintenance while the ship is in port.

In the United States, the United States Department of the Navy's General Order No. 135 issued in 1911 as a formal guide to naval terminology described a naval station as "any establishment for building, manufacturing, docking, repair, supply, or training under control of the Navy. It may also include several establishments". A naval base, by contrast, was "a point from which naval operations may be conducted".

Assistant Secretary of the Navy (ASN) is the title given to certain civilian senior officials in the United States Department of the Navy.

From 1861 to 1954, the assistant secretary of the Navy was the second-highest civilian office in the Department of the Navy (reporting to the United States secretary of the Navy). That role has since been supplanted by the office of Under Secretary of the Navy and the office of Assistant Secretary of the Navy has been abolished. There have, however, been a number of offices bearing the phrase "Assistant Secretary of the Navy" in their title (see below for details).

San Francisco, officially the City and County of San Francisco, is a commercial, financial, and cultural center of Northern California. With an estimated population of 827,526 residents as of 2024, San Francisco proper is the fourth-most populous city in the U.S. state of California and the 17th-most populous in the United States. Among U.S. cities proper with over 300,000 residents, San Francisco is ranked second by population density, first by per capita income, and sixth by aggregate income as of 2023. Depending on how its borders are defined, the broader San Francisco metropolitan area or San Francisco Bay Area is home to 4.6–9.2 million residents. In 2024, the U.S. Census Bureau reported an estimated population of 4,648,486 for the city's metropolitan statistical area (13th-largest in the U.S.) and 9,164,058 residents for the larger combined statistical area (5th-largest).

Prior to European settlement, the modern city proper was inhabited by the Yelamu Ohlone. On June 29, 1776, settlers from New Spain established the Presidio of San Francisco at the Golden Gate, and the Mission San Francisco de Asís a few miles away, both named for Francis of Assisi. The California gold rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. In 1856, San Francisco became a consolidated city-county. After three-quarters of the city was destroyed by the 1906 earthquake and fire, it was quickly rebuilt, hosting the Panama–Pacific International Exposition nine years later. In World War II, it was a major port of embarkation for naval service members shipping out to the Pacific Theater. After the war, the confluence of returning servicemen, significant immigration, liberalizing attitudes, the rise of the beatnik and hippie countercultures, the sexual revolution, opposition to U.S. involvement in the Vietnam War, and other factors led to the Summer of Love and the gay rights movement, cementing San Francisco as a center of liberal activism.

The National Security Act of 1947 (Pub.L. 80-253, 61 Stat. 495, enacted July 26, 1947) was a law enacting major restructuring of the United States government's military and intelligence agencies following World War II. The majority of the provisions of the act took effect on September 18, 1947, the day after the Senate confirmed James Forrestal as the first secretary of defense.

The act merged the Department of the Army (renamed from the Department of War), the Department of the Navy, and the newly established Department of the Air Force (DAF) into the National Military Establishment (NME). The act also created the position of the secretary of defense as the head of the NME. It established the United States Air Force under the DAF, which worked to separate the Army Air Forces into its own service. It also protected the Marine Corps as an independent service under the Department of the Navy. Aside from the unification of the three military departments, the act established the National Security Council and the Central Intelligence Agency, the latter of which is headed by the director of central intelligence.

The United States secretary of defense (SecDef), secondarily titled the secretary of war (SecWar), is the head of the United States Department of Defense (DoD), the executive department of the U.S. Armed Forces, and is a high-ranking member of the cabinet of the United States. The secretary of defense's position of command and authority over the military is second only to that of the president of the United States, who is the commander-in-chief. This position corresponds to what is generally known as a defense minister in many other countries. The president appoints the secretary of defense with the advice and consent of the Senate, and is by custom a member of the Cabinet and by law a member of the National Security Council.

Subject only to the orders of the president, the secretary of defense is in the chain of command and exercises command and control, for both operational and administrative purposes, over all DoD-administered service branches  – the Army, Marine Corps, Navy, Air Force, and Space Force – as well as the Coast Guard when its command and control is transferred to the Department of Defense. Only the secretary of defense (or the president or Congress) can authorize the transfer of operational control of forces between the three military departments (Department of the Army, the Navy, and the Air Force) and the eleven Unified Combatant Commands.

The secretary of the Navy (SECNAV) is a statutory officer (10 U.S.C. § 8013) and the head (chief executive officer) of the Department of the Navy, a military department within the United States Department of Defense. On March 25, 2025, John Phelan was confirmed as Secretary of the Navy.

By law, the secretary of the Navy must be a civilian at least seven years removed from active military service (10 U.S.C. § 8013). The secretary is appointed by the president and requires confirmation by the Senate.