Stuart, Nathan B. Forrest, and John S. Mosby, the Union high command initially failed to understand the proper way to use cavalry during the early stages of the war.

At the time, cavalry units in the Union armies were generally directly attached to infantry corps, divisions, and "wings" to be used as "shock troops," and essentially played minimal roles in early Civil War campaigns.

Only a handful of Union cavalry officers, George Bayard, Benjamin Grierson, and John Buford among them, distinguished themselves in a positive way in the first two years of the war.

Hooker organized three previously unrelated divisions into a single corps of cavalry, placing it under the unified command of George Stoneman.

Worse, Hooker kept only a single division—under Alfred Pleasonton—with the main army to use as scouts or screens while traveling through the dense "Wilderness," accounting in part for the success of Stonewall Jackson's famous flank march on May 2.

Stoneman and division commander William W. Averell were sacked after Chancellorsville, and replaced, respectively, by Alfred Pleasonton and David McM.

Though Pleasonton's men were ultimately defeated, this battle established the Union cavalry as no longer inefficient and overmatched, but a foe to be reckoned with.

Buford's troopers played a major part in slowing Heth's initial advance, and, after being relieved by infantry, spent the rest of July 1 screening and scouting.

The most conspicuous part played by the cavalry during the closing days of the war occurred in the week of March 25–April 1, 1865, when Lee, in a series of bold but understrength and futile counterattacks, tried to break through the Union lines at Fort Stedman.

A week later, at Five Forks, Sheridan's cavalry played a decisive role in repulsing George Pickett's last desperate attack and routing his division.

Sheridan and his men continued to play a major part in harassing Lee's army as it withdrew to Appomattox Court House.

During Sherman's March to the Sea, Kilpatrick's division remained with the army, serving again with a lack of real distinction, while the rest of the cavalry went north with George Thomas to repel John B.