Short answers, pulled from the story.
The Overland Campaign was a series of battles fought in Virginia during May and June 1864, near the end of the American Civil War. Lt. Gen. Ulysses S. Grant directed Union forces against Gen. Robert E. Lee's Army of Northern Virginia, beginning with the crossing of the Rapidan River on the 4th of May, 1864, and concluding with the siege of Petersburg that began in June 1864.
The principal Union commanders were Lt. Gen. Ulysses S. Grant, general-in-chief of all Union armies, and Maj. Gen. George G. Meade, who retained formal command of the Army of the Potomac. Maj. Gen. Philip Sheridan led the Union cavalry. The Confederate forces were commanded by Gen. Robert E. Lee, with corps commanders including James Longstreet, A.P. Hill, and Richard Ewell.
The Overland Campaign was a strategic Union victory. Although Grant suffered severe casualties at battles including the Wilderness, Spotsylvania Court House, and Cold Harbor, he inflicted proportionately higher losses on Lee's army and maneuvered it into a siege at Richmond and Petersburg. Lee's army surrendered in April 1865, ending the Civil War.
At Yellow Tavern on the 11th of May, 1864, Union cavalry under Maj. Gen. Philip Sheridan met Confederate cavalry commander Maj. Gen. J.E.B. Stuart at an abandoned inn 6 miles north of Richmond. Sheridan's force outnumbered Stuart's roughly three divisions to two brigades and carried superior Spencer repeating carbines. Stuart was shot during the battle and died in Richmond the following day. Maj. Gen. Fitzhugh Lee took temporary command of the Confederate cavalry.
The Mule Shoe was an exposed Confederate earthwork salient built during the night of the 8th to the 9th of May, 1864, at Spotsylvania Court House. It extended more than a mile in front of the main Confederate trench line as part of a defensive works stretching more than 4 miles. On the 12th of May, Hancock's II Corps crashed through the salient in a predawn assault; the fighting at the western leg of the Mule Shoe, called the Bloody Angle, continued for nearly 24 hours and produced roughly 9,000 Union and 8,000 Confederate casualties that day alone.
United States Colored Troops under Brig. Gen. Edward A. Wild garrisoned Fort Wilson's Wharf on the James River. On the 24th of May, 1864, Fitzhugh Lee attacked with 2,500 Confederate cavalrymen demanding surrender. Wild's garrison refused and repulsed the assault using musket fire, canister from two 10-pound Parrott rifles, and naval gunfire from the USS Dawn. It was the first significant combat between the Army of Northern Virginia and Black Union soldiers, who successfully defended a fortified position against a larger attacking force.