From the eight sources provided, they indicated that there were less than 50,000 casualties overall in the Overland Campaign which was a series of battles fought in Virginia during the American Civil War.
The Overland Campaign, also known as Grant's Overland Campaign and the Wilderness Campaign, was a series of battles fought in Virginia during May and June 1864, in the American Civil War. Lee surprised Grant by attacking the larger Union army aggressively in the Battle of the Wilderness (May 57), resulting in heavy casualties on both sides. The final major battle of the campaign was waged at Cold Harbor (May 31  June 12), in which Grant gambled that Lee's army was exhausted and ordered a massive assault against strong defensive positions, resulting in disproportionately heavy Union casualties. Both Union and Confederate casualties could be high, but the Union had greater resources to replace lost soldiers and equipment. Multiple attacks by the divisions of the V Corps were repulsed with heavy casualties. May 12 was the most intensive day of fighting during the battle, with Union casualties of about 9,000, Confederate 8,000; the Confederate loss includes about 3,000 prisoners captured in the Mule Shoe. Despite the significant casualties of May 12, Grant was undeterred. Sheridan's raid was an overall tactical success, having killed Jeb Stuart at Yellow Tavern and beaten Fitzhugh Lee at Meadow Bridge, all with relatively minimal casualtiesabout 625 men for the entire raid, compared to 800 Confederate. In the latter case, Sheridan believed it would not have been worth the risk in casualties and he recognized that the chances of holding the city for more than a brief time would be minimal; any advantages would primarily result from damage to Confederate morale. Massive fire from the Confederate lines quickly caused heavy casualties, and the survivors were pinned down. Estimates of casualties that morning are from 3,000 to 7,000 on the Union side, no more than 1,500 on the Confederate. He also suffered relatively heavy casualtiesparticularly in his officer corpsand lost a large number of his horses to battle and heat exhaustion. The campaign was the bloodiest in American history: approximately 55,000 casualties on the Union side (of which 7,600 were killed), 33,600 (4,300 killed) on the Confederate. Estimates vary as to the casualties for the entire campaign. National Park Service 70,139 Bonekemper, Victor, Not a Butcher 87,557 Esposito, West Point Atlas 7595,000 McPherson, Battle Cry 100,000 Rhea, In the Footsteps of Grant and Lee 88,000 Smith, Grant almost
100,000 U.S. War Dept., Official Records 54,926 Young, Lee's Army 33,646 The massive casualties sustained in the campaign were damaging to the Northern war effort. DateMay 4 (1864-05-04)  June 24, 1864 (1864-06-25)LocationVirginiaResult
See Aftermath May 4 (1864-05-04)  June 24, 1864 (1864-06-25) Virginia See Aftermath 103,875124,232 ("present for duty") 60,00065,000 54,926 total
(7,621 killed;
38,339 wounded;
8,966 captured/missing) 30,00035,000 (estimated) 
