The Situation: His brigade commander ordered Major Hyde and his small regiment, the 7th Maine Infantry, to clear the Piper Farm buildings of sharpshooters who were annoying one of his artillery batteries. It was an ill-considered order, as there were significant numbers of Confederate troops - parts of at least 3 brigades - on the farm. Major Hyde and his men made the charge but suffered very high casualties, and returned to their starting point with little gained.
[Confederate]
11th Georgia Infantry
1st Georgia (Regulars) Infantry
7th Georgia Infantry
8th Georgia Infantry
9th Georgia Infantry
2nd Mississippi Infantry Battalion
Brooks (SC) Artillery
1st Texas Infantry
Long Island (VA) Battery
Morris' Louisa (VA) Artillery
Richmond 'Orange' (VA) Artillery
Wise (VA) Legion Artillery, Company D
Source: The Antietam Battlefield Board.1
More on the Web: See Major Hyde's narrative of the charge of the 7th Maine in a post over on the blog.
1 The battlefield position studies by the Antietam Battlefield Board (1904, 1908) are described in the Atlas, which is available online from the Library of Congress.
Carman, Ezra Ayres, and Lieut. Col. Emmor B. Cope, Hays W. Mattern, Charles H. Ourand, Atlas of the Battlefield of Antietam, 14 maps, Washington DC: US Government Printing Office, 1908 [AotW citation 29224]