Third Battle of Petersburg 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 ten - month Siege of Petersburg and leading to the fall of Petersburg and Richmond , Virginia . A . P . Hill was killed in the fighting . Fort Mahone . The Union IX Corps under Maj . Gen . John G . Parke occupied the original trenches captured by the Union army in June 1864 . Facing Parke was a strong Confederate position dominated by Fort Mahone ( named after Maj . Gen . William Mahone ) and manned by the forces of Maj . Gen . John B . Gordon . Since much of the recent actions had been occurring west of Petersburg , in particular the Battle of Five Forks , the Confederate strength east of Petersburg was considerably weakened . On April 1 , 1865 , Parke 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 Maj . Gen . George G . 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 . Boydton Line . 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 Brig . Gen . George W . Getty ' s division at the point with Brig . Gens . Truman Seymour and Frank Wheaton behind . The entire assault against the Boydton Line was carefully planned , and at 4 : 40 a . m . the Vermont Brigade , led by Brig . Gen . Lewis A . Grant , spearheaded the assault - the 5th Vermont reached it first , and Capt . Charles Gould was the first man into the trenches , almost getting killed in the process ; he would later win the Medal of Honor for this action . Twenty minutes later the Confederate lines were broken 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 . At 9 : 00 Hill and Robert E . Lee both learned of the breakthrough . Hill immediately mounted his horse and rode to the Boydton Line to organize its defense . Two stragglers from the 138th Pennsylvania regiment , Cpl . John Mauk , and Private Daniel Wolford , stumbled upon Hill and his aide . Hill demanded their surrender , but the Union soldiers took aim and killed him . His aide rode back to Lee and reported Hill ' s death . Hill had once vowed he would never leave the Petersburg defenses . Forts Gregg and Whitworth . Exploiting the breakthrough was the XXIV Corps under Maj . Gen . John Gibbon . Crossing the Boydton Plank Road , Gibbon turned north and moved towards the city itself . Lt . Gen . James Longstreet was bringing troops down from the Richmond defenses as quickly as possible . To buy time for these troops to take up a position , Brig . Gen . Nathaniel H . Harris made a stand at Forts Gregg and Whitworth . Gibbon was leading his new corps into action for the first time . Led by the division of Brig . Gen . Robert S . Foster , the Federals moved on Fort Gregg . The garrison could not turn back the assault , but once the attackers reached the fort it proved difficult to overrun by sheer momentum . Cannon fire from Fort Whitworth plagued the Federals , but eventually by superior manpower Fort Gregg was overrun . Nearby Fort Whitworth soon followed . Gibbon ' s troops had spent themselves on taking the two forts and now Longstreet ' s corps began to arrive . Hatcher ' s Run Line . The IX Corps was pinned down in Fort Mahone , the VI Corps had run out of momentum after breaking the Boydton Line , and the XXIV Corps had been used up taking Fort Gregg . The only Union Corps left for any further movement was the II Corps under Maj . Gen . Andrew A . Humphreys . Humphreys ' s corps faced the forces of Maj . Gen . Henry Heth running from Hatcher ' s Run to White Oak Road . Maj . Gen . Nelson A . Miles ' s division had been sent to reinforce Maj . Gen . Philip Sheridan on the Union flank . Not needing the infantry support , Sheridan sent Miles back . Once the VI Corps had broken through , Humphreys was ordered to attack along his front . When the order came for Humphreys to attack , Heth had already begun to fall back to a secondary line . Humphreys only had one division available to attack and pushed forward engaging with a few Confederate pickets . When Miles ' s division returned , he faced abandoned trenches . Humphreys wanted to move against Heth , but Meade ordered all the Union infantry to turn and face Petersburg . Humphreys turned to the north , but left Miles behind to deal with Heth . Miles struck Heth at Sutherland ' s Station . Heth , now in command of Hill ' s Third Corps , repulsed two attacks from Miles before the latter sent for reinforcements . As had been the case for the II Corps all morning , Humphreys backtracked to Sutherland Station . However , Miles launched a third assault and broke Heth ' s line . A stand made by a brigade under Brig . Gen . John R . Cooke held up the Federals as the rest of Heth ' s troops headed west . The II Corps had been made to wander back and forth all morning and Humphreys contended that , had his whole corps been allowed to move against the Confederates , Heth ' s whole command would have been destroyed . Aftermath . 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 . Grant had lost approximately 3 , 500 men while Lee lost 4 , 250 men ( including A . P . Hill ) . On April 3 , 1865 , Richmond , now uncovered by Lee ' s army , fell to Union forces . The major objective of the war since 1861 had finally been achieved . A week later Gen . Robert E . Lee would surrender to Lt . Gen . Ulysses S . Grant at Appomattox Court House .