Why was the union campaign between Grant and Lee an integral part in the union victory?

The Union campaign between Grant and Lee was integral to the Union victory because it effectively applied continuous pressure on the Confederate forces, leading to a war of attrition that Lee's army could not sustain. Grant's strategy of relentless engagement, including the Overland Campaign, aimed to deplete Confederate resources and morale. By targeting key locations and employing coordinated offensives, Grant systematically weakened Lee's army, culminating in the surrender at Appomattox Court House, which marked a decisive turning point in the Civil War. This campaign showcased the Union's ability to leverage superior numbers and resources, ultimately leading to the Confederacy's defeat.