Didn't the Union Army employ large numbers of British manufactured Enfield rifled muskets? Wasn't there extensive trade between the Union and Britain through the war?
As has been previously mentioned, if this materiel had been diverted from the North to the South there may have been some different outcomes in some campaigns.
Not too many people have mentioned the other British colonies. India and Egypt were also important producers of cotton, and Britain may have seen it to be in her interest to keep Southern cotton off the world market.
I think the main answers to those both are economic, though they go in opposite directions.
Sale of 1853 Enfields was almost all by private contractors for profit. Both sides bought many, a common estimate is 500k north, 400k south. Not clear and not likely the south would have soaked up the other 500 at the same highly profitable (many fortunes made in CW arms making/dealing) prices. Something like 1.5mil Springfield 1855/61/63/64 were produced (the most common weapon though all kinds of older US and weapons sold from foreign arsenals too) so Enfield purchase was fairly significant. Assuming a reason to reduce gun maker profits it would have had a marginal impact (more guys retaining smoothbores and less effective old Continental purchased rifles, rather than fewer soldiers, probably) that could have tipped some campaign or battle, to not allow sale to the North.
3/4 of Britain's cotton imports in antebellum period were from the US, trending generally higher. Diversification to other exporters (or back to them in India's case, having been displaced by the South) was generally a result of the CW (or just postwar, like Suez Canal in India's case and general world economic growth) rather than preceding it. Moreover many mills were set up for the particulars of American cotton so immediate substitution was difficult; they were screwed for a while, even though obviously the supply was never entirely cut off. Cotton was definitely an economic reason for Britain to be pro-South (anti blockade anyway), conventional wisdom is correct on that one.
Re: third system fort land defences: in general ships alone seldom overcame forts in ACW or elsewhere, properly conducted unbroken land sieges with the right guns almost always did (really anytime after the invention of gunpowder). Again going back to Crimean example, the Sevastopol forts suffered hardly at all from a relatively rapidly deployed naval bombardment, but were reduced gradually by a systematic siege artillery bombardment, similar in both respects to ACW experience. I don't think any coast defence builder of that time would hope for success v. a proper land siege that couldn't be lifted by one's own land forces. But that requires a much better prepared, prolonged and focused effort by the enemy. It is true that geography rendered some forts able to defend waterways but difficult to lay siege to with land guns, with the ranges of that time. The increase in rifled gun ranges was a factor though perhaps in which locations might fall into this category, and how long a siege would take on others, v when the forts were designed.
Edited by JOE BRENNAN, 26 April 2005 - 1200 PM.