The “explosion” was expected to come from New Orleans

From the excellent Perilous Fight by Stephen Budiansky, an account of the naval aspects of the War of 1812. Page 347.

“The Federal Republican, as vehemently anti-administration as ever, predicted in early January 1815 that there was “an explosion at hand; that the President would be called on to resign; and there must be peace by that or a future Administration.” The “explosion” was expected to come from New Orleans: for weeks there had been reports of a huge British naval and military force assembling in Jamaica preparing to launch an attack there. Cochrane had included the city as a likely target back in July in a long list of options he had sent to Melville, and in mid-September approval had come back from London. Whoever controlled New Orleans would control the Mississippi River, and once again Cochrane was convinced the decisive blow was at hand.

On December 16, 1814, after sweeping aside five American navy gunboats guarding the entrance to Lake Borgne, a British invasion force that would eventually reach 6,000 began disembarking at Isle aux Pois, about thirty miles from New Orleans. An advance column of 1,600 men reached the mainland a week later, and three small battles were fought over the ensuing week as the British force probed the defenses around the city.

Andrew Jackson, now a major general in the regular army and in command of the entire district of Louisiana, had chosen his defensive position well. The Mississippi River held his right flank, a cypress swamp his left, and an earthwork parapet protected by a four-foot-deep ditch sheltered nearly five thousand American troops. Seven artillery batteries spaced at fifty- to two-hundred-yard intervals supported the entrenched position, and before the American lines lay a broad open plain that the British would have to traverse to reach them. The British plan was to begin with a night attack to seize two guns that Jackson had unwisely placed in a weakly guarded position across the river, then turn the guns on the main American line as the major British assault began at dawn. But as the Battle of New Orleans began on January 8, 1815, the British attack fell disastrously behind schedule. It was not until daylight that the two guns were seized, and then it took an hour and a half for the main British force to begin its advance toward Jackson’s breastworks. At first a heavy fog shrouded their movement, but it suddenly lifted as the British were still hundreds of yards from their enemy, and the grape and canister began cutting them to pieces. The British commander, General Edward Pakenham, was eviscerated by a blast of grape three hundred yards from the American line as he rode ahead trying to rally his men forward. In half an hour the British lost 2,000 men, including nearly 200 killed and 500 taken prisoner. Total American casualties were 70, and nearly all of those were among the men in the exposed position across the river; the Americans behind Jackson’s breastworks lost 6 killed and 7 wounded. It was one of the most lopsided battles ever fought.