Final answer:
The strategic disagreement between Lee and Longstreet during the Civil War centered around Lee's preference for aggressive offensives while Longstreet was more cautious, with the latter's reluctance highlighted by the direct assault at Gettysburg known as Pickett's Charge.
Step-by-step explanation:
The disagreement concerning strategy between Lee and Longstreet primarily revolved around their approach to engaging Union forces during the Civil War. Lee favored aggressive assaults, aiming to exploit opportunities for tactical victories that could potentially lead to a swift end to the war.
In contrast, Longstreet was more cautious and less inclined to such risky offensives, often favoring defensive maneuvers or flanking movements rather than direct assaults like the infamous Pickett's Charge at the Battle of Gettysburg.
During the Seven Days Battles, Lee's aggressive pursuit and desire for an early decisive victory resulted in a series of encounters that, due to poor execution and lost opportunities, did not yield the destruction of the Union Army as he had hoped.
Again, in the months leading to the end of the war, while the Confederate Army suffered from shortages and disease, Lee's determination to continue the fight clashed with the reality of the deteriorating situation, possibly contrasting with Longstreet's perspectives on the Confederacy's strategic options.
Furthermore, the infamous July 3rd assault, known as Pickett's Charge, was ordered by Lee and led by Longstreet with great reluctance. The disagreement between Lee and Longstreet's strategic preferences is exemplified here, as Longstreet’s reservations about the attack’s likelihood of success were overridden by Lee’s decision to proceed with the direct assault on Union lines.