The correct answer is:
An established government, standing army and industry.
Explanation:
At the beginning of the Civil War, Southern states seceded from the Union because they felt they weren't represented mainly because of the issue of slavery, so Southern states formed the Confederate States, with Jefferson Davis as President; the Northern states believed it would be a short war because they had bigger advantages.
The Northern states had an established and wealthy government recognized by other countries, with a well established structure and with much more experience than the Confederate States. Northern states also had a standing army to go to war and a developed industry that helped them make their firearms and weapons, gunpowder was imported and the Union had power over the navy and controlled the ports.
Even though the Northern states thought it would be a short war, it lasted longer than they believed because Southern states also proved to have big advantages that helped them get through tough times.
