Final answer:
General William T. Sherman's military campaigns, such as the March to the Sea, primarily weakened the Southern economy by destroying both military and civilian resources. Option D is the correct answer.
Step-by-step explanation:
The primary impact of General William T. Sherman's military campaigns during the American Civil War was D. Weakening the Southern economy. Sherman's March to the Sea, which aimed to demoralize the Confederacy, led to widespread destruction of civilian and military resources. By destroying infrastructure, crops, and livestock, Sherman's strategy applied the concept of total war to erode not just the military capabilities of the South but also its economic foundations. This approach indeed weakened the Southern economy significantly, contributing to the eventual collapse of the Confederacy.
Sherman's objective on his March to the Sea was A. to destroy military and civilian resources wherever possible. The Union army, under Sherman's command, looted homes, destroyed crops, burned orchards, and confiscated or killed livestock. By doing so, Sherman sought to break the will and capacity of the South to continue the war.