Fort Canby was constructed during the Civil War.
God knows why.
By 1863, all the hostile Indians had been deported to Shitsville, Oklahoma and the looming threat of the Confederate Navy was confined to Mobile Bay and its environs.
I was stationed there in 1941, a regular Army sergeant on my third and (I thought) final hitch.
I had two privates under me, amusingly named Caine and Abel. The three of us were billeted in a British Nissen hut down the hill from the Cape Disappointment lighthouse.
We played cards, drank coffee, and wrote daily reports. It rained all day, every day. 95% of our reports read Zero Visibility. No activity.
After Pearl, the government came roaring in to throw up buildings and fortifications that included a shielded barbette emplacement of reinforced concrete that contained a six-inch naval gun.
They finished it in 1944, by which time the Japanese Navy was as much a threat as the Rebels had been.