This was the official name of the North during the American Civil War. The soldiers were identified with blue uniforms, and different trim colors according to which ever branch of the army they belonged to. i.e.
Cavalry=Yellow and
Dark Blue; Artillery=Red and Dark Blue.
The Union consisted of 34 states: Maine, Massachusetts, Rhode Island, Connecticut, New Hampshire, Vermont, New York, New Jersey, Delaware, Maryland, Pennsylvania, West Virginia, Ohio, Michigan, Indiana, Illinois, Kentucky, Wisconsin, Missouri, Iowa, Minnesota, Kansas, California, Nevada, Oregon, and others.
After four years of brutal,
off and on fighting, as well as the invasion of Northern States (Kentucky, Indiana, Ohio, West Virginia, Maryland, and Pennsylvania), the determined and enduring stance of
the Union finally prevailed, and the South was defeated.