Why did the confederates defend Petersburg so reiercly?

The Confederates defended Petersburg fiercely because it was a critical supply hub for the Confederate capital of Richmond, Virginia. Its railroads and roads were vital for transporting troops and resources, making it essential for sustaining the Confederate war effort. Additionally, if Petersburg fell, it would open the way for Union forces to capture Richmond, which would be a significant blow to Confederate morale and strategic positioning. The city's defense was thus seen as crucial to prolonging the Confederacy's ability to fight.