The statement "At the beginning of the war, most Union and Confederate soldiers believed the war would be quick and glorious" is true.
Both sides, particularly the Union, believed that the war was going to be quicly. Nevertheless, later on they realized they were wrong.
During the American Civil War, the Union Army was the United States Army, the land force that fought in order to preserve the Union of the collective states.
On the other hand, the soldiers who served in the Confederate States Army fought on behalf of the Confederate States of America.
