A key reason the Union could not hold Fort Sumter was Inadequate resources.

The Union's inability to hold Fort Sumter was primarily due to inadequate resources. As Confederate forces bombarded the fort, Union troops faced severe shortages of essential supplies, including food, ammunition, and reinforcements. These resource limitations significantly hampered their defense efforts, making it increasingly difficult to withstand the prolonged assault. Despite their determination, the lack of necessary provisions ultimately forced the Union to surrender on April 13, 1861. This early defeat highlighted the logistical challenges the Union would face throughout the Civil War and underscored the importance of resource management in military strategy.