At every point Grant was tightening his hold upon the imprisoned garrison and difficulties were crowding fast upon their commander, but he exhibited neither excitement nor alarm. Bending all his energies upon preparations for a retreat, he carefully considered the best plan for moving his troops and supplying their needs on the march, quietly giving his orders to meet emergencies, but allowing no one to see even a shadow of despair on his face. Concerning the gravity of the situation he neither deceived himself nor attempted to deceive others who were entitled to know it, and with absolute accuracy he prophesied the movements of his adversary long before they were made. ..."You may expect Sheridan to move up the Valley," he wrote the Confederate Secretary of War.... "Grant, I think, is now preparing to draw out by his left with the intent of enveloping me. He may wait till his other columns approach nearer, or he may be preparing to anticipate my withdrawal. I cannot tell yet.... Everything of value should be removed from Richmond. It is of the first importance to save all the powder. The cavalry and artillery of the army are still scattered for want of provender and our supply and ammunition trains, which ought to be with the army in case of a sudden movement, are absent collecting provisions and forage. You will see to what straits we are reduced; but I trust to work out." At last, on March 29th, 1865, Grant pushed forward 50,000 cavalry and infantry to execute the very move which Lee had outlined and for which he was as thoroughly prepared as it was possible to be with the men he had on hand. But to check this advance which threatened to surround his army and cut off his retreat, he had to withdraw the troops guarding the defenses of Petersburg, abandoning some of the intrenchments altogether and leaving nothing much more formidable than a skirmish line anywhere along his front. Even then he could not stop the onrush of the Union troops, which, under Sheridan, circled his right on April 1st and drove back his men in the fierce engagement known as the battle of Five Forks. With the news of this success Grant promptly ordered an assault against the intrenchments and his troops tore through the almost defenseless lines in several places, encountering little or no resistance. Petersburg was not yet taken, but Lee immediately saw that to protect it further would be to sacrifice his entire army. He, therefore, sent a dispatch to Richmond, advising the immediate evacuation of the city. "I see no prospect of doing more than hold our position here till night. I am not certain that I can do that," he wrote. But he did hold on till the Confederate authorities had made their escape, and then on the night of April 2nd he abandoned the capital which he had successfully defended for four years and started on a hazardous retreat.