Most people don't know much about our military. When veterans are asked if they served, they usually hear "what's the army like?" I usually respond with "I wouldn't know, I'm a Marine" which draws confused looks from my interrogator. This post will differentiate between branches and also illustrate the responsibilities and capabilities of each branch.
The United States Armed Forces consist of seven 'uniformed service branches'. The Army, Navy, Marine Corps and Air Force are the main combat branches and fall under the Department of Defense, which is headquartered at the Pentagon in Arlington, Virginia. The Coast Guard is considered a branch of the military, but falls under the Department of Homeland Security. The National Oceanic and Atmospheric Administration and the Public Health Service are considered uniformed branches because they can have commissioned officers through the US Navy.
Under the Department of Defense, each branch has its own civilian-led administrative department (the army falls under the Department of the Army, Navy & Marine Corps under Department of the Navy, Air Force under Department of the Air Force). Each department is led by a secretary that oversees the management of each service branch.
Each branch also has its own senior military staff, led by a general and a senior enlisted adviser who act as policy makers for the military. In the Marine Corps, the Commandant is a four-star general who is in charge of the entire Corps; he is assisted by the Sergeant Major of the Marine Corps, his senior enlisted adviser.
The branches
The Army
The United States Armed Forces consisted of a total of over 3 million service members total in the mid-2010s. Of that number, 1 million of them are in the US Army.
The Army was created on June 10, 1775 (making it the oldest branch) by the Continental Congress to fight the British Empire during the Revolutionary War.
The army's job in the US Armed Forces is as the primary ground fighting branch. Since its creation, the US Army has fought in every conflict that involved Americans, attaining victory against the British in the Revolutionary War and War of 1812, and constituting itself as the Union during the American Civil War. The US Army was also active in the Indian Wars through most of the 19th Century, and was also involved in storied fighting in both World Wars, the Korean War, Vietnam War, and several smaller conflicts throughout the 1980s and 1990s.
Today, the US Army is heavily engaged in the Global War on Terrorism, being responsible for the bulk of ground fighting in Iraq and Afghanistan. The US Army has a reserve component, the US Army Reserve, and also has a National Guard Bureau that is responsible for the defense of each of the 50 states and America's external territories.
The Navy
The US Navy is the largest naval force in the world in terms of number of ships and their combined tonnage.
Created on October 14, 1775 the Navy's primary mission is that of the United States' maritime force. The Navy has roughly half a million members, with its own reserve component.
Aside from fighting at sea, the Navy is one of two branches responsible for carrying out our nation's nuclear deterrence (the other being the Air Force). The Navy also maintains ten aircraft carriers, the largest force in the world, and operates nearly 3,000 combat aircraft.
The Navy is well known for being the first force in the world to utilize submarines, the first force to sail under the North Pole, the first force to harness nuclear power, and the force that killed Osama bin Laden, the warlord of al-Qaeda who masterminded and ordered the 9/11 terrorist attacks.
The US Navy's most well-known actions were in World War Two, when it led the Pacific War against Japan and also participated in the largest amphibious assault in history, the D-Day landings in France, in 1944.
The Navy also possesses one of the world's deadliest special operations units, the Navy SEALs, which were created by President John F. Kennedy in 1962.
Like the Army, the Navy is heavily engaged in the Global War on Terrorism, and has also participated in every US conflict.
The Marine Corps
The US Marine Corps is considered one of the most respected, well-trained and deadly fighting forces the world has ever seen.
Created in a bar in Philadelphia on November 10, 1775 the Marine Corps is a force of 'sea soldiers', which means it can fight on land and sea (and in the air now, once it developed its own aviation component in 1912).
The Marines have a reputation as hard-hitting and ferocious fighters, earning themselves the moniker 'Teufel Heunden' (Devil Dogs) from the Germans in World War One.
Today, the active duty force contains 195,000 Marines (the largest force of its kind in the world), and has roughly 30,000 reservists scattered throughout units in 48 of the 50 states.
Whereas the US Army has ten active duty divisions and several independent brigades and regiments, the Marine Corps has three active duty 'Marine Expeditionary Forces' which consist of a division, an air wing, and a logistics group. The reserves are centered around a division, air wing and logistics group but are not organized as a MEF.
The Marine Corps has fought in every US conflict since the Revolutionary War, and even in some conflicts where the army was not involved. Because of its amphibious nature, US Marines are on ships around the world and are often the first responders to natural disasters and conflicts everywhere. US Marines were first on the ground in the aftermath of the 2004 tsunami in Indonesia, and are also called on to evacuate civilians during unrest in war-torn countries.
The Air Force
Aviation within the United States military was slow to catch on, with the Wright Brothers inspiring the US Army to adopt the airplane into its inventory by 1907. The Navy would follow less than two years later, and the Marine Corps again in 1912.
As a whole, most aviation was overseen by the Army, with the creation of the Army Air Corps in 1926. The Army Air Corps became the Army Air Force in 1942 after the US realized they needed a more comprehensive aerial force to fight the Germans and Japanese in World War Two.
After the war, seeing the importance of an air force, the US Air Force was created separately from the Army in 1947 with the passing of the National Security Act.
Since then, the Air Force has dominated the skies in the Korean War, the Vietnam War, Desert Storm, several NATO actions, and the Global War on Terrorism.
The US Air Force is the largest aerial combat force in the world only behind the Chinese People's Liberation Army Air Force. Like the Navy, it is tasked with nuclear deterrence, possessing intercontinental ballistic missiles and nuclear bombs. The Air Force is also tasked with cyber warfare and space warfare, being responsible for spy satellites and computer defenses.
The US Air Force has around 320,000 airmen on active duty and 150,000 reservists in both the Air Force Reserve and the Air National Guard. The US Air Force also has the largest number of transport aircraft in the world, making it the first choice in the US military when it comes to moving people and equipment by air. They are sought out by military and civilian groups alike for their ability to move large amounts of men and supplies to disaster zones and battlefields. They have even flown Shamu the whale from one park to another because there was no other way to transport the whale.
Honorable mention: The Coast Guard
The US Coast Guard, created in 1790 as the Revenue Cutter Service, is a law enforcement branch that has the distinction of being the world's 12th largest naval force by itself (with the US Navy being first and the British Royal Navy second).
The Coast Guard was officially created out of a merger of the Revenue Cutter Service and US Lifesaving Service in 1916, and was subsequently placed under the Department of Transportation. Aside from being under Department of the Navy during both World Wars, the Coast Guard remained under DoT until 9/11, when the Coast Guard was placed in the newly formed Department of Homeland Security.
The US Coast Guard active duty force has 40,000 sailors and has a unique role in that it is the only branch allowed powers of arrest. Other than protecting US waterways and trade routes, the Coast Guard serves as a force that oversees the lawful use of fisheries and protection of international shipping routes. The Coast Guard is also the premier service utilized for life-saving; Coast Guard helicopters have executed some of the most daring water rescues in US history (see "The Guardian", starring Ashton Kutcher and Kevin Costner).
The Coast Guard is also a leading force in the fight against drug importation. The Coast Guard's most notable operation was during Hurricane Katrina in August 2005, when the branch as a whole was awarded the Presidential Unit Citation for rescuing over 33,000 people from New Orleans by air alone over the course of a week.
A Brief Side note:
-Personnel in the US Army, Army Reserve, and Army National Guard are referred to as 'soldiers'
-Personnel in the US Navy and Navy Reserve are referred to as 'sailors'
-Personnel in the US Marine Corps and Marine Corps Reserve are referred to as 'Marines'
-Personnel in the US Air Force, Air Force Reserve and Air National Guard are referred to as 'airmen'
-Personnel in the US Coast Guard, Coast Guard Reserve and Coast Guard Auxiliary are referred to as 'Coast Guardsmen'
