Final answer:
Confederate General Robert E. Lee told the Confederate government that he could no longer defend Richmond after Grant's Army of the Potomac captured a key railroad junction.
Step-by-step explanation:
When General Ulysses S. Grant's Army of the Potomac captured a vital railroad junction southwest of Petersburg, it was the beginning of the end for the Confederate capital. Confederate General Robert E. Lee informed the Confederate government that he could no longer defend the city of Richmond.
This was a critical moment in the Civil War, as it signified the loss of the Confederate capital and led to General Lee's retreat toward Lynchburg, setting the stage for the eventual surrender at Appomattox Court House.