In preparing for a presentation on Lincoln’s involvement in weapons, I learned a bit more about the Trent Affair that many may not be aware of.
We no doubt are all familiar with the Trent affair, and with Lincoln’s decision to return the captured Confederates Mason and Slidell, who had been removed from the British mail steamer Trent, rather than risk war with England. “One war at a time” is said to have been his remark. My recent reading of Robert Bruce’s book Lincoln and the Tools of War (Bobbs-Merrill, 1956) delves deeper into issues that surely played a part in his decision.
There are two elements in the Trent Affair of which I don’t recall hearing of previously. One concerned the supply of potassium nitrate (niter or salt-peter) which was needed for gunpowder. The second was protection of northern ports.
Regarding niter, most of it at that time came from India, a British possession. By May, the Du Pont Company advised that only a six months’ supply remained the in the U.S. In an attempt to ensure a supply, the Navy had sent a man to England to quietly obtain all that was available. The purchases had been made and were being loaded for shipment when the Trent affair broke. When it did, the British prohibited all export of niter.
Regarding protection of northern ports, it should be noted that the British were already armoring some of its ships. It should also be noted that, while rifled cannon were deemed to be superior to smooth-bore guns, those in control of ordnance continued to feel that smooth-bored was better, although the newer rifled canon would be needed to penetrate an armored ship. Around this same time, McClellan had set up a Military Armament Board to decide on the best field artillery and cannon for fortifications. After a review by six distinguished military men, the board realized that there were not any guns protecting northern ports that would be capable of defending against even a lightly armored ship.
The failure to release Mason and Slidell surely would make the critical supply of niter unavailable for prosecuting the war, and could easily lead to war with Britain. When it was then realized that any armored British ship could sail into any northern port with little fear of serious damage, and the ensuing disaster for the Union was a real possibility, it is no wonder that Lincoln felt that “one war at a time” was wise, and had the men released.