At the outset of the Civil War, the United States consisted of 34 states and 32 million people. It had a regular army of just 15,322 enlisted men and 1,080 officers that were mostly scattered on the western frontier.
Each state had its own militia. In Ohio, the militia consisted of mostly town folks who dressed up for special parades and holidays. Militia members elected their officers, not on merit or abilities, but on their popularity or position in the community.
Each militia unit could choose their own uniforms. Training usually meant learning how to accomplish parade maneuvers without bumping into one and other. All together, before the start of the war, Ohio had just over 1,000 militia members. By the end of the war, almost 320,000 soldiers participating in the war would be from Ohio. Only New York and Pennsylvania would have contributed more than Ohio.
Immediately after the onset of the war, the ranks of the militia grew at an unimaginable rate. As quickly as someone requested to form a company, the company was filled with would-be soldiers.
The initial enlistment period was just 90 days. Feeling that the rebellion would soon be quashed, there was no need to ask for longer enlistments from these citizen soldiers.