Named for Revolutionary War general and South Carolina native Thomas Sumter, Fort Sumter was one of nearly 50 forts built as part of the so-called Third System, a coastal defense program implemented by Congress in 1817.
In simple terms, the U.S. Armed Forces are made up of the five armed service branches: Air Force, Army, Coast Guard, Marine Corps, and Navy.
The United States Army (USA) is the largest branch of the United States Armed Forces and performs land-based military operations.n 1941, the  Army of the United States  was founded to fight World War II. The Regular Army, Army of the United States, the National Guard, and Officer/Enlisted Reserve Corps (ORC and ERC) existed simultaneously. After World War II, the ORC and ERC were combined into the United States Army Reserve.