How did the Northern and Southern strategies change during the Civil War?

Gradually the North realized that it's initial strategy of dealing a crippling blow early on to the South was unrealistic and with the South's strong leadership and highly motivated armies, one could argue it was downright impossible. What the North did have was a massive superiority in men and material meaning that the North could continue the fight much longer than the South could. Eventually Northern strategy began to reflect this as Union commanders began to simply attack Southern commanders relentlessly, all the while knowing that their losses could be replaced but that the Southerners were increasingly being depleted of men and resources and even those that were left were quickly becoming exhausted with no means to replace them. Other Northern generals--especially William T. Sherman--realized that the South's greatest strength was her spirit and so they set out to attack that directly. They plundered, looted, destroyed, raped, and pillaged through Georgia and burned Atlanta to the ground in order to break Southern morale, which was already teetering on the brink after so many years of war. In another less famous though equally important slash-and-burn campaign, Northern armies destroyed the Shenandoah Valley, which had been the lifeblood of Stonewall Jackson's Army and indeed of many units of the Army of Northern Virginia. As for the Southern strategy--that was largely dependent on the individual Southern commander. Lee chose an extremely aggressive strategy in order to break the North's spirit by inflicting massive losses and giving himself and his Army of Northern Virginia an air of invincibility. In order to accomplish this, Lee primarily remained in Virginia throughout the war relying on his troops knowledge of terrain and fierce desire to protect their homes to keep his army functioning. It was when Lee left Virginia--Antietam and Gettysburg--that he suffered some serious setbacks (although Antietam was a draw, Lee still failed to achieve his objective and threaten the North directly). I would say Lee's strategy didn't change that much, which was perhaps his downfall, although given the circumstances I don't think he could have done anymore than he did. After Grant's relentless pursuit of Lee and the siege of Petersburg, Lee was simply drained of all his resources and had to capitulate.