Final answer:
The Civil War began when Confederate forces fired upon Fort Sumter on April 12, 1861, following President Lincoln's intent to resupply the fort without any aggressive moves.
Step-by-step explanation:
The Civil War began when Confederate forces fired upon Fort Sumter in Charleston, South Carolina. This event took place on April 12, 1861, and marked the beginning of conflict between the Confederacy and the Union. Contrary to other possible scenarios, it was not a celebration of a peaceful resolution, nor did the Union surrender the fort prior to the attack, and neither did the Union forces launch a surprise attack on Charleston, nor did they receive an order from the Union's military commander to fire on the Confederates. The Confederate forces did not begin firing as a direct result of Union provocation; they fired because President Lincoln intended to resupply Fort Sumter, and the Confederates viewed this action as a threat to their sovereignty.