thumb|110px|Brigadier general insignia
A brigadier general in the United States Army, Air Force, and Marine Corps, is a one-star general officer, with the pay grade of O-7. Brigadier general ranks above a colonel and below major general. Brigadier general is equivalent to the rank of rear admiral (lower half) in the other uniformed services.

Statutory limits

U.S. Code of law explicitly limits the total number of general officers that may be on active duty. The total of active duty general officers is capped at 302 for the Army, 279 for the Air Force, and 80 for the Marine Corps. Some of these slots are reserved by statute.

Promotion, appointment and tour length

For promotion to the permanent grade of brigadier general, eligible officers are screened by a promotion board consisting of general officers from their branch of service. This promotion board then generates a list of officers it recommends for promotion to general rank. This list is then sent to the service secretary and the joint chiefs for review before it can be sent to the President, through the defense secretary for consideration. The President nominates officers to be promoted from this list with the advice of the Secretary of Defense, the service secretary, and if applicable, the service's chief of staff or commandant. The President may nominate any eligible officer who is not on the recommended list if it serves in the interest of the nation, but this is extremely rare. The Senate must then confirm the nominee by a majority vote before the officer can be promoted. Once a nominee is confirmed, they are promoted to that rank once they assume a position of office that requires an officer of that rank. For positions of office reserved by statute, the President nominates an officer for appointment to fill that position. For all three uniformed services, because the grade of brigadier general is a permanent rank, the nominee may still be screened by an in-service promotion board to get their input on the nominee before the nomination can be sent to the Senate for approval. Since the grade of brigadier general is permanent, the rank does not expire when the officer vacates a one-star position. Tour length varies depending on the position, by statute, and/or when the officer receives a new assignment but the average tour length per one-star billet is two to four years.

Retirement

Other than voluntary retirement, statute sets a number of mandates for retirement. All brigadier generals must retire after five years in grade or 30 years of service, whichever is later, unless selected or appointed for promotion, or reappointed to grade to serve longer. Otherwise all general officers must retire the month after their 64th birthday. However, the Secretary of Defense can defer a general officer's retirement until the officer's 66th birthday and the President can defer it until the officer's 68th birthday. General officers typically retire well in advance of the statutory age and service limits, so as not to impede the upward career mobility of their juniors.

History

The rank of Brigadier General has existed in the United States armed forces since the American Revolutionary War. A brigadier general was, at first, strictly an infantry officer who commanded a brigade; however, over the course of the 19th and 20th centuries, the responsibilities of the rank expanded significantly.

During the period from March 16, 1802 to January 11, 1812, the rank of Major General was abolished and Brigadier General became the highest rank in the U.S. Army. Foreseeing the need for an expanded general staff in case of war, which seemed imminent, Congress restored the rank of Major General in January 1812.

The first Brigadier General in the U.S. Marine Corps was Commandant Archibald Henderson, promoted to the rank of brevet Brigadier General in the 1830s for his service in the Second Seminole War. The first non-brevet Brigadier General in the Marines was Commandant Jacob Zeilin who was promoted to the rank in 1874, but when he retired in 1876, Colonel once again became the highest rank in the Marines until March 1899 when Commandant Charles Heywood was promoted. Ever since then the office of Commandant has been held by a general officer, with the permanent rank of the Commandant raised to Major General in 1908 and to first Lieutenant General and then General during World War II, which rank it has held ever since.

The insignia for a brigadier general is one silver star worn on the shoulder or collar, and has not changed since the creation of the rank two centuries ago. Since the Mexican-American War, however, the lower rank of colonel has been the normal rank appointed to command a brigade.

Today, an Army or Marine Corps "BG" typically serves as Deputy Commander to the Commanding General of a division or division-sized units and assists in overseeing the planning and coordination of a mission. In an infantry brigade not attached to a division, a Brigadier General serves as the unit's commander, while a Colonel serves as deputy commander. An Air Force brigadier general typically commands a large wing. Additionally, one-star officers of all services may serve as high-level staff officers in large military organizations.