If you're in the military, it's a pretty safe bet that you know how your service branch is organized. But each service is different, and if you work in a joint-service atmosphere, it might help you to know each branch's chain of command.
Or you might just be a civilian who wants to know what a soldier means when he says, "I'm with Charlie Company, 2nd Battalion, 501st Parachute Infantry Regiment, 1st Brigade Combat Team, 82nd Airborne Division." Because, let's be honest — that's a lot harder to decipher than a civilian saying, "I work on the account management team."
While the structural organizations of three of the four service branches are pretty straightforward (Navy, you are NOT in that category), they each have a few distinct exceptions that only service members in those branches would know.
For example, when it comes to the Army's largest unit — the Army Region — it's only used in large-scale war and hasn't been in effect since World War II. Similarly, the Air Force has numbered units toward the top of the chain that are also mostly just used during wartime.
While the U.S. Marine Corps falls under the Department of the Navy, its command structure is similar to that of the Army, except it follows the 'rule of three' — three of each smaller unit to a bigger unit — and has aircraft wings that follow completely different naming terminology.
As for the Navy's structural organization? Well … let's just call it what it is — confusing. Unlike the other branches, the Navy has two chains of command — operational and administrative, which can sometimes overlap, and depending on where a sailor is assigned, he or she might be part of both. In fact, it's so confusing that the Bluejacket's Manual, which is essential reading for all new recruits, warns sailors of that.
Luckily for you, we've broken down the units on a special interactive page: