In July, Grant had ordered an operation to dig a sapper tunnel under the Confederate defenses. The 36th Wisconsin, with II Corps, was ordered to make a feint towards Richmond, Virginia, to force General Lee to dilute the defense of Petersburg before the detonation of the mine. Lee responded by sending 16,500 men to reinforce Richmond. The First Battle of Deep Bottom, which started on July 27, had the desired effect as Lee sent more forces north to reinforce Richmond. On the night of July 29, the Union force quietly abandoned their feint and forced a march back toward Petersburg, arriving in time to witness the failure of the attack in the Battle of the Crater.