I did not know this.

The first "professional standing army" of the United States was formed by General Washington and headed by General Wayne and was called the "Legion of the United States". Trained at the first basic US military training facility at Legionville, Pennslyvania. The legions troops were called "Legionnaires". The size of the legion being set by Congress in 1795 at 4,800 total.

I always thought it was called the United States Army...who would have thunk?