Final answer:
The Civil War began when Confederate forces fired on Fort Sumter, initiating the conflict between the Union and the Confederacy.
Step-by-step explanation:
The Civil War began when Confederate artillery fired on Fort Sumter, despite warnings that if the South were to fire first, it would unite northern public opinion against secession. This act of aggression marked the start of the war between the Union (the northern states) and the Confederacy (the southern states).
President Jefferson Davis did not order Major Robert Anderson to abandon Fort Sumter and engage in diplomacy. Instead, the Confederate forces attacked the fort, leading to the outbreak of the Civil War.
Learn more about Causes of the Civil War