The War of 1812 is perhaps the United States' least known conflict. Other than Andrew Jackson's 1815 victory at New Orleans and Francis Scott Key's poem "The Star-Spangled Banner" written in 1814 during the British attack on Baltimore, most Americans know little about the country's second major war. Its causes are still debated by historians today. Great Britain's impressment of American sailors, its seizure of American ships on the high seas, and suspected British encouragement of Indian opposition to further American settlement on the western frontier all contributed to America's decision to declare war against Great Britain in June 1812.

None of these factors, however, adequately explain why President James Madison called for a war the country was ill-prepared to wage. Moreover, the war was quite unpopular from the start. Many Federalists—chiefly in the New England states—opposed an armed conflict with Great Britain, continued to trade with the British, and even met in convention to propose secession from the Union. Some members of the president's own Republican Party objected to the war's inevitable costs and questionable objectives, such as the conquest of Canada.

To declare war was one thing, but to prosecute it successfully was a different matter. Much of the story of the War of 1812 is about the unpreparedness of America's Army and Navy at the conflict's outset, and the enormous difficulties the new nation faced in raising troops, finding competent officers, and supplying its forces. Most of America's military leaders were inexperienced and performed poorly, particularly in the first two years of war. Only gradually did better leaders rise to the top to command the more disciplined and well-trained units that America eventually fielded. But despite costly initial setbacks, by the time the fighting stopped American arms had won key victories at Chippewa, Lundy's Lane, and New Orleans under excellent officers such as Winfield Scott, Jacob Brown, and Andrew Jackson. Although the United States achieved few of its political objectives in the War of 1812, its Regular Army emerged more professional, better led, and fit to take its place as the foundation of America's national defenses.

Situated between the states of Maryland and Virginia, the Chesapeake Bay was America's largest estuary. The bay and the watershed it served were home to vibrant agricultural and fishing activities; important ports (Baltimore, Maryland, and Norfolk, Virginia); a major naval construction yard at Portsmouth, Virginia; and last but not least, the nation's capital, Washington, D.C. Threaten these, the British reasoned, and America might shift its focus from trying to conquer Canada to defending its own homeland. Consequently, in December 1812 the British Secretary of State for War and the Colonies, Lord Henry Bathurst, directed Adm. Sir John Borlase Warren to impose a limited blockade of the American coast, with particular attention to the Chesapeake Bay. The lead elements of the British blockading force arrived at the mouth of the bay in February 1813 to begin what would become a two-year campaign.