alternatehistory.com

9 September

A meeting takes place, in which the Mayor of Charleston reluctantly agrees to apologize in all particulars for the mistreatment of the British ships in the recent incidents and in which the prosecution of those involved is agreed to. The Confederate government undertakes to rebuild Charleston's defences, and of course to furnish the full asisstance of the Confederate navy in any future incident (subject to that incident not falling foul of the now-passed Foreign Relations Act).

11 September

The HMS Great Eastern leaves Charleston, having unloaded most of the remaining military supplies to replenish those expended by the RN squadron and the ground force. It has instead been loaded with thousands upon thousands of former slaves, not just men but women and children as well.
The Great Eastern's destination in the short term is Halifax, from whence the newly-emancipated slaves will be able to travel where there are places for them. This shipment largely clears the last of those within the British perimeter, though this is mainly because a substantial fraction of the slaves in or near Charleston were moved elsewhere before the British secured control.


14 September

Lenthall produces a sketch design for a deep-draft ironclad along the “Defence type” lines as requested by Congress. His design notes that the armament is subject to change, but currently is listed as 30 8” Parrott rifles, and has a 4.5” armour belt amidships and on the battery (tapering to 2” at the ends).
This design is essentially an armour clad version of the Niagara of a few years previous in gross hull form, which has made the design process much simpler, though the shift to iron construction Lenthall has noted as “potentially problematic” but one he declares should be fully considered.



15 September

Asked to clarify on the matter of armament, Lenthall suggests alternate configurations for the deep-draft ironclad's armament. Without making major changes to other factors, he notes that he could mount:

30 8” rifles
20 of the newly designed 10” rifles
8 15” smoothbores
4 20” smoothbores
Or some combination thereof.
He is requested to increase the armour to at least 6” amidships and 3” at the ends, though he warns this will cut roughly 20% off the armament weight.

16 September

The Royal Naval squadron and their infantry battalions begin withdrawing from Charleston. Progress is slowed partly by how some few thousand additional slaves have crossed into the British region in the hopes of being emancipated.

17 September

Lenthall's design is asked to be modified further to allow for better cruising radius – she should be able to cross the Atlantic under steam if need be. The ends are reduced back to 2” and the battery to 5.5”, and he is asked for a 2:1 ratio of 8” guns to 10” guns.

20 September

Lenthall delivers his paper design, asking somewhat sarcastically if this is the final revision. He is told it is for now, and asked to produce some more detailed plans.

The paper ship is a somewhat more full-bodied version of the Niagara with a slightly greater length, fitted with 3 10” rifles and 8 8” rifles on each broadside along with a pair of 10” pivot rifles fore and aft. She has 5.5” armour on the belt and battery, with a 2” belt protection along the ends, and has a top speed under steam of 12 knots.
The primary downside of the design is that it makes certain assumptions about US shipbuilding capability, particularly about the ability to produce 5.5” single thickness plate – though in a pinch it is considered possible to produce the required protection by using 4.5” discard plate from the Royal Navy and adding a 1” layer midway through the timber backing. This would impair protection compared to a full 5.5” plate, but would at least reduce damage from a Palliser shell or the like.

She is noted to be superior in every way to HMS Defence. (The Warrior is carefully not mentioned, as the comparison here is more murky.)