They severed the last railroad lifeline into Atlanta, making the Citadel of the confederacy as it was touted no longer tenable.
In the 1950s, the confederacy, the Northeast, and the Midwest all had about the same populations.
Some claim that you are biased in your history against the confederacy and weigh slavery as a cause for the war too heavily.
late 14c., from Anglo-French confederacie (Old French confederacie), from stem of Latin confoederatio, from confoederare (see confederate). Earliest in reference to leagues of classical Greek states (Aetolian, Achaean, etc.), later of the Netherlands. The word was used of the United States of America under (and in) the Articles of Confederation (1777-1788). In reference to the breakaway Confederate States of America (1861-1865) from 1861.
Confederacy now usually implies a looser or more temporary association than confederation, which is applied to a union of states organized on an intentionally permanent basis. [OED]