A subtle point made by Lieutenant-Colonel William Ames in his in-progress report on the Third Major Bombardment, on July 27, 1964, was the attrition rate of the heavy Parrott rifles. These guns – the 6.4-inch (100-pounders), 8-inch (200-pounders), and 10-inch (300-pounders) – not only threw the greatest weight, but were more frequently used in the Third Major Bombardment than their smaller brothers. The loss of one gun burst and two out of action for repairs put limits on the sustained rate of fire against Fort Sumter. Another approaching limitation on the firing rate was the supply of ammunition. Having expended over 6,000 rounds by month’s end, even the large stockpiles on Morris and Folly Island were drained.
If the pace of fire slackened, the Confederates would have more time to repair. Major-General John Foster could not have that. He wanted to knock the fort down. More so, Foster wanted to increase the pace, if possible, by adding more guns to the bombardment. Reluctant to wait for more shipments from the north, he inquired with Rear-Admiral John Dahlgren on July 30, 1864:
I have the honor to request the loan of six 100-pounder Parrott guns, to be placed in a new battery erected on Cumming’s Point. I also beg leave to say that I will avail myself of your offer of some 9-inch guns for the battery at Spanish Wells, and will send for them in a day or two. I shall be obliged to borrow of you the ammunition for these guns, as we have none.
Dahlgren, in the spirit of good joint operations, responded promptly:
Conformable to your request, six 100-pounder Parrotts will be loaned to you, and are at your disposal when it suits your convenience to send for them. I expected to have obtained the 9-inch guns from the Wabash, but she has left this port, and I have required on the Bureau for some. When they arrive I shall be glad to meet your wishes.
On paper there were “Army” and “Navy” models of these large Parrott rifles. But the only notable difference between the models were the markings. All Parrotts larger than 5.2-inch (30-pounder) had blade-type cascabels with breeching blocks. Sight arrangements varied for mountings on ironclads, pivot batteries, or army siege carriages. But those were fittings modified locally by artificers. These were guns which Foster could put into battery without delay.
As for the 9-inch guns requested, eventually the Navy loaned some of those, as captured in a wartime photograph:
Unlike the Parrotts, the Dahlgren gun required a wooden carriage, seen here. Looks rather out of place sitting on a wooden platform in the beach sand.
(Citations from OR, Series I, Volume 35, Part II, Serial 66, pages 200-2.)