My brother is in the Navy, It is the branch of the Armed Forces that is designated for naval and amphibious warfare,
Nice, I have relatives who were in the Navy too.
The branch includes anything conducted by ships, submarines, and seaborne aviation.
When was the branch created?
I am not sure, but the US Navy has 332,421 personnel on active duty and 107,577 in the reserve.
That's fewer people than I thought. 
It is the third largest of the service branches.