After teaching for two years, he attended the United States Military Academy, graduated in 1837 ranked 24th of 50, and was commissioned a second lieutenant in the U.S. Army's artillery branch.

[5] Even though many of these supplies failed to arrive, Sedgwick still managed to erect comfortable stone buildings for his men before the cold weather set in.

At the start of the American Civil War, Sedgwick was serving as a colonel and assistant inspector general of the Military Department of Washington.

In the Battle of Antietam, II Corps commander Maj. Gen. Edwin V. Sumner impulsively sent Sedgwick's division in a mass assault without proper reconnaissance.

Sedgwick was slow to take action, but eventually crossed the Rappahannock River and assaulted Maj. Gen. Jubal Early's small force on Marye's Heights on May 3 during the Second Battle of Fredericksburg.

At the Battle of Gettysburg, his corps arrived late on July 2, and as a result only a few units were able to take part in the final Union counterattacks in the Wheatfield.

While much of Sedgwick's VI Corps was held in reserve at Gettysburg, it performed exceptionally at the Second Battle of Rappahannock Station in November, capturing four field pieces, eight stands of enemy colors and 1,700 prisoners.

[6] Prior to the start of the Overland Campaign in the spring of 1864, George Meade reorganized the Army of the Potomac and dropped several underperforming generals.

Sedgwick narrowly missed the chopping block, being that he was unpopular with Secretary of War Edwin Stanton for being a vocal admirer of departed Army of the Potomac commander George McClellan and for having shown insufficient enthusiasm for abolitionism and the Radical Republican platform.

Confederate sharpshooters were about 1,000 yards (900 m) away, and their shots caused members of his staff, infantrymen from the 87th Pennsylvania and 14th New Jersey, and artillerymen from the 1st Massachusetts, to duck for cover.

when his face turned slowly to me, and blood spurting from his left cheek under the eye in a steady stream, brought to me the first knowledge of our great disaster.

Corps medical personnel were immediately summoned, but Sedgwick never regained consciousness and continued to bleed out for some time, until his hair was soaked with blood.

Meade had recently quarreled with Sedgwick for being over-reliant on fellow corps commander Gouverneur Warren for advice, and said of him "I wish we could have parted on better terms."

Ulysses S. Grant characterized Sedgwick as one who "was never at fault when serious work was to be done" and he told his staff that the loss for him was worse than that of an entire division.

Academy legend has it that a cadet who spins the rowels of the spurs on the boots of the statue at midnight while wearing full parade dress gray over white uniform under arms will have good luck on his or her final exam.