Adam Badeau, Military history of Ulysses S. Grant from April 1861 to April 1865. Volume 2

All west of the rebel centre had now been driven beyond the Appomattox by Sheridan, while all to the east was forced into Petersburg, from which there was no exit for Lee except by the country roads north of the river. The only question with Grant was, whether at once to assault the inner lines or wait for the rebels to move out from behind their works, and attack them in flight and undefended. The troops in front of Petersburg had been under arms for eighteen hours; they had assaulted the strongest lines known in modern war, swept down them several miles, and, returning, marched five miles east of the original point of attack; they were too exhausted for another assault, unless it was absolutely necessary. Meade and others entitled to offer their opinions urged strongly that the whole army should be brought up to Petersburg, and the place assaulted in force; but Grant did not doubt that Lee had already determined upon flight, and a further assault of fortified works would only occasion unnecessary slaughter. He therefore decided to envelop the town on the southern side of the Appomattox, but to hold half his army in readiness for prompt pursuit. If the rebels should not withdraw, he meant, of course, to assault in the morning; but, if Lee evacuated the city in the night, the national troops in front of the town could take prompt possession of Petersburg, while Sheridan, and those disposed along the Appomattox, would be ready to intercept and pursue the flying columns. No assault was therefore ordered for the 2nd of April.