The process and reasons for the U.S. declaration.
The Declaration of War of June 18, 1812, is the first formal declaration of war under the U.S. Constitution. Analyzing it as a primary source reveals the stated grievances against Great Britain, the constitutional process, and the political and ideological divisions within the early republic.
On June 18, 1812, the United States declared war on Great Britain for the first time under the Constitution, citing impressment, illegal blockades, the Orders in Council, and British influence on Indigenous nations. The declaration, signed by President James Madison, initiated the War of 1812 and tested the young republic’s sovereignty.
In June 1812, the U.S. House and Senate narrowly approved the first declaration of war in American history, with the House voting 79–49 and the Senate 19–13. The votes were sharply partisan—every Federalist voted no, while a quarter of Republicans also opposed or abstained—revealing deep divisions over relations with Britain.
