Brockville (originally Elizabethtown) is the oldest incorporated city in the Province of Ontario. Its present name was chosen as a patriotic act in the summer of 1812 to honour the great commander General Brock. Major-General Sir Isaac Brock, memorialized as one of Canada's outstanding military heroes, is commemorated with a plaque at St Peter Port Church on the Isle of Guernsey where he was born. He entered the British Army in 1785 and, in 1802, he was posted to Canada with his regiment. In 1811, just prior to the outbreak of War, Brock became President of the Executive Council and Administrator of Upper Canada (Ontario). He rapidly organized the defence of the new colony. His leadership culminated in the capture of Detroit. General Brock was killed at the Battle of Queenston Heights, 1812, and he is buried on the battlefield.

During the war, Brockville was attacked by a force of 200 regulars and militia from Morristown who came across the frozen St Lawrence River (February, 1813). The detachment was led by Major Benjamin Forsyth of the United States Army. The village was garrisoned by a company of Leeds militia who, taken by surprise, could offer no resistance. The raiders released prisoners from the jail, took a quantity of arms, horses and cattle, and carried off a number of residents. The resentment aroused by this raid led to the successful British attack on Ogdensburg a fortnight later.

Gananoque played an essential role as a forwarding point on the supply line moving along the upper St Lawrence River from Montreal and Cornwall to Kingston. An incursion of regulars and militia led by the Captain Forsyth of the 1st US Rifle regiment made an attack here (September 1812). A detachment of the 2nd Leeds militia, under Colonel Joel Stone, offered some resistance, but withdrew its force of two subalterns and about 40 soldiers. American forces seized the stores, burned the government depot, and withdrew.

Parks Canada and the citizens of Prescott, the "Fort Town", proudly conserve Fort Wellington National Historic Site. Like Fort Henry, the current fort was built later (1837) on the ruins of the original fort that was used in the War of 1812, along with a shore battery by the river, to defend this area’s part of the St Lawrence River supply route. Prescott is home to a British military hospital and barracks (one of the earliest surviving military buildings in Ontario). Colonel Edward Jessup, the founder of the community, and many disbanded members of Jessup’s Rangers settled in Leeds and Grenville Counties, 1784. Colonel Jessup was the first leader of the local militia.

Prescott keeps alive the heroic and spontaneous action of the Glengarry Light Infantry, whose impulsive leader, Lieutenant-Colonel “Red George” Macdonell led a force of 480 regulars and militia over the frozen St Lawrence River (against artillery) and captured the military post at Ogdensburg, February 1813. The attack was made in response to the recent raid on Brockville; however, it was contrary to the orders of Sir George Prevost, Captain General and Governor in Chief of British North America. Advancing across the ice in two columns, Macdonell's right column presented an easy target for the enemy artillery, but after a fierce fight, the reinforced left column forced the American rifle regiment to withdraw. American military stores were captured and the schooners burned. This successful assault across the ice ended the occupation of Ogdensburg by American forces for the remainder of the war and it helped make secure the St Lawrence supply link between Upper (Ontario) and Lower Canada (Quebec).

Today, Brockville, along with Gananoque and Kingston are three major gateways to the celebrated international Thousand Islands region of the St Lawrence River; known by First Nations as The Garden of the Great Spirit. In waterways used by American and British warships in the War of 1812, Canada’s smallest national park (1904) preserves these exquisite islands which are a tiny land bridge uniting the immense Canadian Shield and the Adirondack Mountains of the eastern United States and Canada.