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?"