Final answer:
The War of 1812, known as "Mr. Madison's War" to the British, was prompted by British impressment of American sailors and disrespect for U.S. sovereignty, ultimately leading to Madison's declaration of war despite his initial aversion to it.
Step-by-step explanation:
The 19th-century war referred to derisively by the British public as "Mr. Madison's War" was the War of 1812. This conflict arose primarily due to British impressment of American sailors, as well as other grievances related to the disrespect for the sovereignty of the United States. British sea captains' desperate need for crew members during the Napoleonic Wars led to them taking American sailors to work on British ships, inflaming American sentiment. President Madison, facing intense pressure from Congress and the public and despite his personal opposition to war, declared war on June 1, 1812. The war witnessed the burning of Washington, D.C., and the celebrated Battle of New Orleans, which happened after the Treaty of Ghent had technically ended the war. The wave of discontent with the war, particularly among the Federalists in New England, even led to the Hartford Convention where the possibility of secession was discussed, ultimately contributing to the decline of the Federalist Party.