The third Battle of Petersburg, also known as the Breakthrough at Petersburg or the Fall of Petersburg, was a decisive Union assault on the Confederate trenches, ending the 10-month Siege of Petersburg and leading to the fall of Petersburg and Richmond. With Confederate defeat at Five Forks on April 1, Gen. Ulysses S. Grant and Maj. Gen. George Meade ordered a general assault against the Petersburg lines by II, IX, VI and XXIV Corps.
On April 1, Maj. Gen. John G. Parke and his IX Corps chose to assault Fort Mahone directly. The attack carried the fortress and the trenches around the Jerusalem Plank Road. The attack slowed down once the Federals occupied the captured trenches. Gordon rallied the troops and planned a counterattack to drive Parke out of his lost trenches. With the complete disintegration of the Confederate army around Petersburg just hours away, Parke sent word to Meade for reinforcements to simply hold his current position. Late in the afternoon in the midst of all other Confederate fronts collapsing, Gordon launched his counterattack and nearly drove Parke out. The Federals held their position and Union reinforcements began to arrive.
Maj. Gen. Horatio G. Wright was forming his VI Corps for a massive assault against the Boydton Line held by Lt. Gen. A.P. Hill. Wright massed his entire corps in a wedge with Maj. Gen. George W. Getty's division at the point with Brig. Gen. Truman Seymour and Brig. Gen. Frank Wheaton behind.
On April 2, from 12:00 A.M. to 2:00 A.M., a bombardment covered the noise of 14,000 men moving into no-man’s-land. The entire assault against the Boydton Line was carefully planned. The plan was to attack at 4:00 A.M., and a feint by 1st Division of IX Corps took a bit of trench and drew in Confederate reserves. At 4:40 A.M., the Vermont Brigade, led by Brig. Gen. Lewis A. Grant, spearheaded the assault. The Confederate lines were broken 20 minutes later and a decisive breakthrough had been achieved. Wright turned his corps to the south as the Union XXIV Corps exploited the breakthrough. Stragglers from the initial breakthrough continued heading straight forward as the rest of the VI Corps turned to the left. They got to the South Side Railroad and started wrecking the rails, as well as pillaging a wagon train that had arrived with supplies and the camps of Gen. Robert E. Lee’s normal reserve division.
To the east, IX Corps didn’t break through everything, but did push the Confederates back to the last line of defenses. At 9:00 A.M., Hill and Lee both learned of the breakthrough. Hill immediately mounted his horse and rode to the Boydton Line. Two stragglers from a Pennsylvania regiment ambushed Hill and his aide. Hill demanded their surrender, but the Union soldiers took aim and killed him and his aide. Hill had once vowed he would never leave the Petersburg defenses. Lee looked at the situation and told the Secretary of War that he would have to evacuate that same day. Breckinridge immediately sent a messenger to President Jefferson Davis to tell him the grave news. He left the church service that he was at at the time.
Lee had to cobble together a line from remnants and artillery, and he had to deploy a battery just south of his own headquarters. The 6 guns repelled the charge of a weak, tired Union division, but when the Federals began turning the flank the gunners had to withdraw. Lee was the last to leave the position; he got more personally involved in the fighting than normal and may have been seeking death in battle to avoid the agony of a failing campaign.
After midday, the fighting dwindled to one area: Fort Gregg and Fort Baldwin, the linchpins of the last Confederate line. Brig. Gen. John Gibbon led about 5,000 men of his XXIV Corps to the attack across swampy ground. If the Confederate defenders had more men it would have been foolish, but there were only 300 infantry and 2 guns, and there wasn’t much supporting fire from other forts. Several attacks were repelled, but the Confederates ran out of cannon shells, then bullets, and were reduced to throwing rocks. After a half-hour of hand-to-hand combat they were all prisoners or dead. Gibbon knew his men were still ready to go, and he headed for Fort Baldwin – but not head-on. He sent out sharpshooters and deployed his men – success was so obvious that the Confederates withdrew and Gibbon marched in.
Grant saw that his men were winded, and he also saw that Lee’s withdrawal was inevitable, so he didn’t press the attack. Lee spent his afternoon organizing the withdrawal – what units would move down which roads when, how many guns and supplies to get out, and things like that. About 8:00 P.M. the withdrawal began, and 30,000 men pulled out overnight. Grant had achieved one of the major military objectives of the war: the capture of Petersburg, which led to the fall of Richmond, the Capitol of the Confederacy.
The Breakthrough at Petersburg ended the Siege of Petersburg and began Lee's retreat to the west, where he hoped to obtain supplies and link up with Gen. Joseph E. Johnston's army in North Carolina.
On April 3, Richmond, now uncovered by Lee's army, fell to Union forces. The major objective of the war since 1861 had finally been achieved.