What's in a Formation? Examining John Hatch's Attack Formations at Second Manassas and South Mountain

John Porter Hatch

There are many books and sources related to the American Civil War (okay, that's an understatement). Despite that fact, it always amazes me how much we still do not know about that war and its participants and battles. As historians, we always need to ask the "why" questions to learn more: why did an event transpire the way it did and why is that event worth telling? Of the five Ws always worth asking, "why" is, at least to me, the most intriguing.

Sorry for my history soapbox here, but asking why something happened or why someone made one decision over another can lead us down interesting investigative paths that may force us to think about outside influences on a battlefield commander's decision-making process and what their intent may have been with the decision path they chose.

Take, for example, the attack of Fitz John Porter's Fifth Corps (with John Hatch's division attached) against "Stonewall" Jackson's lines at the Deep Cut during the Battle of Second Manassas on August 30, 1862. It's a story of incredible human drama and carnage, the largest Federal attack during that battle, and, it could be argued, it paves the way for John Pope's defeat on the Manassas battlefield. But it is also a unique attack during the Civil War. At its onset, Porter's command was stacked in a formation six lines deep with a frontage of approximately 400 yards. Sacrificing width for depth, the attack formation eventually expanded to a frontage of about 830 yards, more than double its initial width. Naturally, while examining this assault, the question came up in my mind: "Why is Porter's command in this formation for its attack?"

Porter's and Hatch's formation of successive lines prior to their attack against the Deep Cut on August 30, 1862

I turned to a 2012 edition of Blue & Gray Magazine that focused on the August 30, 1862, actions at Second Manassas. Inside, historian Jamie Ryan provided commentary on Porter's formation:

The unique attack formation adopted by Porter's force resulted from a compromise between Pope's demand for a pursuit of a retreating force and the reality on the ground. Butterfield's two brigades (Roberts' and Weeks') started the attack with a regiment-wide line of battle, followed by successive units in the only formation that could resemble a column of pursuit yet transform fairly quickly into a line of battle: columns of divisions doubled on the center. That is, each of these regiments deployed two companies in a line formation followed by four other companies in line so that the ten companies were bunched into two columns, five companies deep.

Ryan's narrative continued about the deployment of Hatch's division on Porter's right.

Hatch's division...also adopted a unique formation. The proximity of the lines deprived Hatch of the use of a skirmish line, so he formed his division in six successive lines, the first four being two regiments wide. Hatch's formation was quite similar to the "revolutionary" formation that Emory Upton would adopt attacking Spotsylvania's "Mule Shoe" on May 10, 1864.

This painting of Porter's attack at the Deep Cut shows the successive lines of
the Federal assault

Historian Earl Hess, based on comments in his book Civil War Infantry Tactics, would describe Porter's and Hatch's formations as one of successive lines rather than an attack column. "[A] column consisted of a stack of battle lines placed very close behind each other--only a few feet to a few yards," Hess says. "Successive lines were placed much farther apart from each other--hundreds of yards in fact." Hess further elaborated on the pros of utilizing a formation of successive lines on the battlefield. They "allowed for much more tactical flexibility than did columns. There was much to be gained by organizing the available force in two or more battle lines, including depth in defense and support for the first line in an attack. If nothing else, multiple lines gave a sense of security and confidence to a harried commander who was worried about the outcome of an engagement."

Thus, it seemed the answer was found. Porter's and Hatch's formations stemmed from a compromise between two competing objectives: pursuit and assault. Also, the formation allowed flexibility for the assault as the rear lines could either be used to aid the front lines in withdrawing from a dangerous situation or exploit any advantage the front lines might enjoy.

However, the questions about this formation carry forward two weeks to September 14, 1862, when John Hatch deployed his division in a similar fashion to assault enemy positions north of Turner's Gap. Early campaign historian Ezra Carman described the formation as follows: "The general order of battle was for two regiments of Patrick's Brigade to precede the main body, as skirmishers, supported by the two remaining regiments of the brigade, these to be followed at 200 paces by Phelps' Brigade, and Phelps in turn by Doubleday's, at the same interval."

Abner Doubleday's hand-drawn map of Hatch's attack formation at the
Battle of South Mountain

Arriving at the "why" behind the similar deployment of Hatch's division at South Mountain is not as straightforward. In To Antietam Creek, author Scott Hartwig speculates that Hatch deployed his command in a similar fashion to the August 30, 1862, attack "due to the reduced strength of his division and the formidable nature of the position to be assaulted." This seems plausible. Assaulting up the terrain north of Turner's Gap was difficult. Again, Hatch valued flexibility and keeping his options open as the fight developed. However, it might seem just as true that Hatch and his men knew this formation well and resorted to their division's institutional knowledge to deploy on September 14. This formation was useful in assaulting well-defended positions. For Hatch's men, it failed at Second Manassas but worked on at South Mountain.