The US Civil War was fought by officers trained at West Point where they had been taught the theories of Jomini, learned tactical deployments based on those of Napoleon and studied the railway-based campaigns fought in Europe over the previous couple of decades. They had also taken Dunant’s views to heart and medical services in the US military were among the best in the world. In the harsh classroom of the battlefield they would realize that none of these had really prepared them for the realities of war in the industrial age.
The reasons for the outbreak of the war were rooted in decades old disputes about the powers and rights of the federal US government contrasted with those of the individual states. The issue that gave the spark was slavery, supported in the agrarian southern states but opposed in the industrialized northern states. The dispute led several southern states to pass legislation to secede from the USA, the north retaliated by declaring that no state could legally secede. The first shot came from southern artillery batteries firing on Fort Sumter to enforce its surrender.
The armed forces of the USA at this date dictated the early phases of the war. The federal government had control of the US Army and US Navy, but was faced by the fact that many of the best officers and men left at once to return to their southern states. Each state had its own militia, but these were of variable quality with widely differing levels of training and equipment. The southern, or Confederate States, began the war with around 120,000 men who were generally of better fighting qualities than the 150,000 men fielded by the northern or Unionist States. The Confederates had no navy to speak of, while the Unionists had all 80 ships of the US Navy, albeit that most of them were obsolete and undercrewed.
Both sides realized the advantages of railways both to move troops and to keep them supplied. Indeed the Confederates won the first major battle of the war, First Bull Run on 21 July 1861 after they brought up reinforcements by train. However, the over reliance on rail meant that major operations were limited to areas which could be supplied by rail. This restricted the theatres of operations and removed the ability of either side to engage in strategic manoeuvres.
Both sides likewise noted the way Moltke had used telegraph to keep in touch with his scattered armies. The Confederates used telegraph as primarily a means to send information and orders between generals. The Unionists, on the other hand, used the telegraph principally to send messages and orders from the civilian government in Washington to generals in the field. President Lincoln’s habit of interfering in the day to day conduct of campaigns drove his generals to distraction.