Why did the Conferderates defend Petersburg so fiercely?

The Confederates defended Petersburg fiercely because it was a critical supply hub for the Confederate Army, providing essential resources and reinforcements to sustain their efforts in the Civil War. Its loss would have jeopardized the defense of Richmond, the Confederate capital, making it a strategic priority. Additionally, the city's extensive network of railroads was vital for transporting troops and supplies, further emphasizing its importance in the overall war strategy. The prolonged siege at Petersburg demonstrated the desperation and determination of the Confederate forces to hold onto this key position.