He didn't have many options, apart from starving and being carried to jail.
However, he could have told his troops to take to the hills and conduct guerrilla warfare, as some of his officers wanted. He refused this, and reluctantly ordered a formal surrender.
Because he tried to keep it going despit Lee's surrender.
What are the causes of when Lee met Grant and agreed to surrender ?
Lee surrendered at Appomattox.
General Lee did not surrender in Atlanta. He surrendered at Appomattox Court House in Virginia.
Appomattox.
Richmond
Appomatox
The immediate problem was the army's rations going astray. But that army was barefoot and starving anyway. And it had run out of manpower.
he DID surrender.
Virginia
lee surrendered to grant at Appotamox courthouse
Lee surrendered to Grant because Lee had lost so many soldiers and was running out of weapon and supplies, so Lee had to surrender. Lee surrendered April 9 1865 but was not official until April 12 1865. When Lee surrendered all the the other commander and soldiers starting surrendering. The last surrender was in July 1865.