Note that Fort Wood is the original name of what is now known as Fort Macomb.It is certainly interesting to think about. I've read a couple of "alternative histories" - not the political stuff that changes what happened, but rather what-if novels such as Led Deighton's SS-GB about the Nazis taking over Great Britain - and they are interesting to strike up the imagination. I really think a foreign invader would have a really rough time getting past our coastal defenses at New Orleans. The Fortifications Board knew the importance of that city and put a lot of resources there - six forts and three other fortifications - to make sure that didn't happen. Remember that part of the Union capability during the Civil War rested on the fact that the attackers had all the fortification plans and even used the engineers that built the forts in designing the attacks. Additionally, the Confederacy had very limited resources spread over a very large area. In the case of a foreign invader, the roles would have been reversed with the attackers having limited resources (due to distance from their home bases) and would be blind to our defenses. They were a reasonable well-kept secret when it came to details.
In his 1821 Report, Bernard outlined a strategy of how to attack New York City and what our response would be prior to the Third System. It might be fun to build a strategy for an invader attempting to take New Orleans and play it out with the Third System in place!
The following graphic is one that I put together for a presentation on the defenses of New Orleans. The green arrows indicate the three principal routes of attack that a foreign invader might use in staging an attack on the city. Note that Ship Island (location of Fort Massachusetts) is where the British staged their attack during the War of 1812, and Bayou Bienvenue (location of Battery Bienvenue) is the route they used toward the city. Note that they didn't even try to attack Fort St. Philip, even though Fort Jackson didn't exist at that time.
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