1 1/2 pages, 7 7/8 x 9 3/4 in., creased, with some separations along few creases and small holes to left margin of both leaves. 

McClellan writes in response to Colonel Henry Larcom Abbot's letter of 21 August, which included the results of Abbot's artillery experiments, giving advice on the storming of Fort Wagner and similar forts. In part: "I am inclined to think that an elaborate system of experiments upon the breaching of thick parapets of sand & earth would be of interest just now - altho' I expect Wagner and its companions will have to be taken in some such way as the [?] was, viz: drive the garrison into their bombproofs by mortar firing, & then march into the work before they can get out of their shelters. Gilmore [sic] will have to use more mortars before he gets through."

President Lincoln had relieved McClellan of command the previous November owing to his reticence to take an aggressive approach, culminating in the lost opportunity at Antietam. Colonel Abbot, considered a brilliant engineer, had been put in charge of a brigade in the defense of Washington in May of 1863, and apparently took advantage of the lack of action to conduct artillery experiments. The taking of Fort Wagner in Charleston Harbor surely would have been at the top of the list of subjects requiring further analysis. Union forces had already stormed the fort twice in 1863, losing 339 men to the Confederates' 12 on July 11 and 1,515 to 174 a week later (the latter battle being best remembered for the valiant charge of the African American 54th Massachusetts). McClellan's letter probably did not make it to Abbot and on to Major General Quincy Gillmore in time to be of any use, but the successful attack was similar to what McClellan suggested. Generals Alfred Terry and Thomas Stevenson had led assaults that captured the fort's rifle pits by August 25, but were unable to progress further. On the date of McClellan's letter, General Gillmore shifted his attention from Fort Sumter to Fort Wagner, commencing a 36-hour shelling of the fort with the assistance of Admiral Dahlgren's forces, after which the Confederate garrison found itself unequipped to fend off the siege forces dug into the pits. They quickly evacuated, and Union forces walked into Fort Wagner on 7 September.