Scott Hartwig, foremost Civil War historian, retired Supervisory Historian at Gettysburg National Military Park, and author of the 700-page tour-de-force To Antietam Creek, adjudged Hunt “immensely talented,” “instrumental” in the victory at Malvern Hill, “meticulous” and who “worked tirelessly” to place the guns of the Army of the Potomac in a position to gain victory. McClellan regarded him as “the best living commander of field-artillery,” a “man with the utmost coolness in danger … an admirable organizer, a soldier of a very high order.” McClellan, an organizational genius himself, praised Hunt’s merit “not only in organizing his command to the best advantage, but in using it on the field of battle with the utmost skill and power.” Bruce Catton called him “one of the most useful officers the Union Army possessed,” a “solid fighting man.” Most relevant, Catton classified him as “keen student of the new science of gunnery” and advocate for “great massed sheaves of gunfire.” America’s greatest Civil War historian went so far as to opine that if Hunt had been allowed to put this strategy into practice at Gettysburg, Pickett’s historic charge would never have reached the Union line.
In 2003, the first-ever biography of Hunt was published. Under Hunt, his biographer recounted, “the artillery of the main Federal army in the eastern theater attained a prominence not equaled by any other branch of the service on either side.” During the Civil War he won widespread praise from comrades and enemies, and dozens of reports by superiors recommended him “for the highest honors the army could bestow.” U.S. Grant reacted to a Hunt idea by writing “I will take advantage of Gen. Hunt’s suggestions.” He appointed him to have general charge of the siege operations once Lee was pinned behind the Richmond/Petersburg defenses in the summer of 1864. During the final attack by the Army of Northern Virginia, on March 25, 1865, at Fort Steadman, Grant relied on Hunt as a substitute for the Army of the Potomac’s commander, George Meade, who was away, directing the front-line commander to address his needs for reinforcements, both infantry and artillery, to Hunt. The attack commenced just after 6:00 a.m.; Hunt quickly had reinforcements in motion, giving Grant a status report that “I sent down at once” units from both arms and sent for more infantry.
At Antietam, Catton wrote, Hunt’s strategy was to have twenty to thirty guns concentrate at a time on a Confederate battery, “shifting to another when they had put the first out of action.” That he succeeded in getting to this critical readiness is a tale unto itself.
When McClellan was withdrawn from the James Peninsula, the landing at Aquia Creek, Virginia served as a staging area south and in proximity to Washington. Hunt had brought the Artillery Reserve there beginning on July 21. He quickly forwarded batteries to the Army of Virginia under Pope as they could be organized, furnishing a dozen by the time the battle of Second Manassas occurred. Hunt was at Alexandria with most of the Reserve during the two-day affair, and he commuted to the capital to learn what was happening.
On September 5, Hunt accepted McClellan’s offer to become chief of artillery. He had hesitated because the position had previously been solely administrative, accepting when McClellan gave him full authority over battlefield deployment of all batteries, not just the Reserve, as well as all of the stuff. Since Lee was in Maryland and the Army of the Potomac was on the chase, no time existed to fully implement the change. Hunt “had his hands full” inventorying the units and their condition and putting them into fighting trim. He found shortages and disarray; he “attacked the problems with characteristic vigor.” The task was daunting while the army marched. In only nine days he “accomplished miracles in putting the army’s batteries in fighting condition.” By the 17th, the army had sixty-four batteries with 323 guns upon which to rely.
Hunt downplayed his after-action report, saying it was brief and that details from the various artillery units associated with infantry would provide full information. His summary, however, proved much more than that. He began with the situation on the 5th: “I found the artillery much disorganized.” Though normally requiring time to sort out properly, the exigencies of the situation faced by McClellan meant that Hunt worked so “that as rapidly as batteries could be equipped they should be pushed forward, without regard to the troops with which they belonged.” Accordingly, he forwarded them as fast as completed where they were assigned to whatever divisions were ready to march. This urgency only complicated matters. “When the army left Washington, I was compelled to obtain on the roads the names and condition of the batteries and the troops to which they were attached.” Despite these obstacles, Hunt indefatigably equipped and provisioned the artillery such that, he could vow, “by the time the artillery reached the Antietam it was (considering the condition in which the disastrous campaign in August had left it) very respectably provided.” He did not claim special circumstances but admitted this arm had been stitched together like the rest of the army. He did mention, however, that he had done so with only one officer on his staff.
Hunt also reported how the artillery played key roles during various stages of the campaign, during the advance from Frederick after the Lost Orders changed McClellan’s plan, at the battle of South Mountain, during September 16 and 17, and finally at Shepherdstown. Summarizing, he wrote: “The artillery attached to the divisions performed their duties creditably and gallantly, and there were many instances of desperate fighting. The enemy repeatedly attempted to carry our batteries, but were in every instance driven back, a circumstance due in a great degree to the care taken in posting their supports.”
 Hartwig, pp. 151, 158-160.
 George B. McClellan, McClellan's Own Story: The War for the Union, The Soldiers Who Fought It, The Civilians Who Directed It and His Relations to It and to Them, William C. Prime ed. (New York: Charles L. Webster & Co., 1887), p. 117.
 McClellan's Own Story, p. 117.
 Bruce Catton, Glory Road (Garden City, N.Y.: Doubleday & Company, 1952), pp. 36; Mr. Lincoln’s Army (Garden City, N.Y.: Doubleday & Company, 1951, 1962), p. 191.
 Edward G. Longacre, The Man Behind the Guns: A Military Biography of General Henry J. Hunt, Chief of Artillery, Army of the Potomac (Cambridge: Da Capo Press, 2003), pp. 11-12.
 The Papers of Ulysses S. Grant, Vol. 10: January 1-May 31, 1864, ed. John Y. Simon (Southern Illinois Press, 1967), p. 309.
 The Papers of Ulysses S. Grant, Vol. 11: June 1-August 15, 1864, ed. John Y. Simon (Southern Illinois Press, 1967), p. 141.
 The Papers of Ulysses S. Grant, Vol. 14: February 21-April 30, 1865, ed. John Y. Simon (Southern Illinois Press, 1967), pp. 217-219.
 Glory Road, p. 290.
 Edward G. Longacre, The Man Behind the Guns: A Military Biography of General Henry J. Hunt, Chief of Artillery, Army of the Potomac (Cambridge: Da Capo Press, 2003), pp. 116-118.
 OR, Vol. XIX, part I, 205.
 Hartwig, pp. 151, 158-159.
 OR, Vol. XIX, part I, 205-207.