The Napoleonic Wars raged in Europe from 1803 to 1815 and had a global impact. Wishing to remain neutral and assert its independence, the United States continued to trade with both Britain and France. Nevertheless, diplomatic relations between the U.S. and Britain deteriorated. Forced labour and deplorable conditions on British naval vessels resulted in sailor desertions to the U.S. by the thousands. The U.S. resented the impressment by the British Navy of sailors from American ships. Meanwhile, Britain’s support of the First Nations in the American northwest threatened U.S. expansion. Not all voices clamoured for war, but a persuasive American political faction called the War Hawks emerged who believed victory over British North America would be “a mere matter of marching”.
On June 18, 1812, the United States declared war on Great Britain. Niagara was a focal point. The British had forts at both ends of the Niagara River (Fort George and Fort Erie) to protect the peninsula from invasion. The major American military base in the region was Fort Niagara, dominating the head of the Niagara River in Youngstown, New York, across from Fort George.
In October of 1812, a U.S. force invaded at Queenston Heights. For three years, Niagara was under almost constant siege.
The war resumed in the spring of 1813, with better prepared U.S. forces. An American victory at York (Toronto) encouraged a new Niagara campaign. In May, a landing force captured Fort George. They held onto the Fort until December of 1813, at various times expanding and contracting from that point. Most of Niagara then was under U.S. occupation. When the Americans withdrew in December, they burned the village of Niagara (Niagara-on-the-Lake).
In 1814, the U.S. invaded Niagara again. This time the focus was to the south, at Fort Erie. They captured the Fort and proceeded into the peninsula again, with engagements at Chippawa (July 5, 1814) and then Lundy’s Lane (July 25, 1814). Following these two devastating clashes, the U.S. withdrew to Fort Erie and endured a British siege of the fort (August 15 - September 17). In November, however, compelled to reinforce their eastern seaboard, the U.S. retreated across the border and the occupation of the Niagara Frontier was over.
"You may consider war as inevitable. It will take place in July at the latest. Upper Canada will be the first object. Military stores of all kinds and provisions are daily sending from hence towards the lines; 13,500 militia, the quota of this state, are drawn and ordered to being readiness at a moment's notice."
"We are miserably deficient."