What was the successful strategy for winning the civil war?

Answer 1

The confederacy
Prolonged fighting until the northern spirit broke

(New respondent)

I think that's back to front.

Grant won the war by ending the sysem of prisoner exchange, so the Confederates were bound to run out of men first. Then he simply forced the fighting till they were depleted by desertions, and all barefoot and starving.

Grant's strategy, upon becoming overall commander, was an elaboration of Scott's Anaconda Plan. With the blockade firmly in place, he used the Army of the Potomac to fix Lee's Army of Northern Virginia in a defense of Richmond while he sent Sheridan through the Shenandoah Valley to cut them off from supplies, reinforcements, and intelligence; while he sent Sherman into the Deep South to destroy the South's infrastructure, crops, transportation, and communications, to starve the Army and deprive it of arms, ammunition, and every material needed to wage war.