Final answer:
Fort Sumter was the property of the Union government.
Step-by-step explanation:
At the start of the Civil War, Fort Sumter was the property of the CUnion government. Fort Sumter is located in Charleston, South Carolina, and it was built as a coastal defense fortification. It played a significant role in the outbreak of the Civil War when Confederate forces attacked and ultimately captured the fort.
Learn more about Fort Sumter's ownership at the start of the Civil War