Which Federal Brigade suffered the most casualties (proportionately) at Antietam? An Imperfect Analysis

   Civil War arithmetic is never an exact science--let's get that out of the way first. Hence, the information below is likely an imperfect analysis of the posed question: which infantry brigade in the Army of the Potomac suffered, proportionately, the greatest number of casualties on September 17, 1862?

The attack of Fairchild's Brigade was sketched in the battle's aftermath

   After combing through the casualty returns found in Volume 19, Part I, of the Official Records, and the strength figures granted each brigade by Ezra Carman, here are the results this exercise has produced:

	Strength	Losses	Percentage
Hartsuff (1st Corps)	1,000	599	59.9
Fairchild (9th Corps)	943	455	48.25
Dana (2nd Corps)	1,946	898	46.15

   Admittedly, this study is, as aforementioned, imperfect. Firstly, Carman's strength figure for George Hartsuff's Brigade is an estimate.(1) Additionally, the strength of Harrison Fairchild's Brigade, traditionally the brigade receiving this grisly distinction, is disputed. Matthew Graham's regimental history of the 9th New York Infantry and the casualty charts in the Official Records agree on the number of losses, though Carman's and Graham's strength figures differ (Carman's was used in the above calculations). Graham claims the brigade went into action with lighter numbers, perhaps about 860 men. Regardless, the proportionate losses using this lesser number equate to 52.91%.(2)
   The strength figures of George Hartsuff's Brigade has been less scrutinized since the battle. But could it be that Hartsuff's losses amounted to nearly 60% of the brigade's battle strength? Using Carman's numbers and the Official Records, it appears that Hartsuff's Brigade, for now, is associated with this gruesome label.


Notes:
(1) Carman, The Maryland Campaign of September 1862, Volume II: Antietam, 64.
(2) Ibid., 581.