At that moment — Virginia lost, Washington menaced, Maryland invaded — the national cause could afford no risks of defeat.
One battle lost, and almost all would have been lost.
Lee's army might then have marched as it pleased on Washington, Baltimore, Philadelphia, or New York.
It could have levied its supplies from a fertile and undevastated country; extorted tribute from wealthy and populous cities; and nowhere east of the Alleghanies was there another organized force able to arrest its ts purposes, although offensive in its character, and would be technically called a defensive-offensive campaign.
It was undertaken at a time when our army had experienced severe defeats, and its object was to preserve the national capital and Baltimore, to protect Pennsylvania from invasion, and to drive the enemy out of Maryland.
These purposes were fully and finally accomplished by the battle of Antietam, which brought the Army of the Potomac into what might be termed an accidental positio