In mid-April 1813, a large American flotilla of ships sailed out of Sackett's Harbour, across Lake Ontario from Kingston, Upper Canada. The ships carried 1,600 American regulars and militia under the command of Brigadier-General Zebulon Pike. The force landed on the north shore of Lake Ontario three kilometres west of York (Toronto.
The British commander in York, Major-General Roger Sheaffe, had 300 British troops under his command. The militia units were in a state of panic as the Americans approached the town. Major-General Sheaffe, decided to evacuate York. Before the British troops withdrew, they set lit fuses in the main gunpowder magazine near the barracks and set the two British ships in the harbour afire.
As the Americans advanced to the magazine, a deafening roar shattered the morning air. The concussion of the explosion threw many American troops to the ground. Within moments, a lethal shower of rocks and debris descended on the shaken soldiers. The blast killed over 200 American troops, and Brigadier-General Pike was among the fatalities.
The Americans occupied York for the next four days, seizing anything that might be of value. On the morning of 30 April 1813, fires began to break out in York. Although American officers had ordered their troops not to destroy civilian property, several soldiers ignored these instructions. By noon, flames engulfed York. The Americans departed and sailed back to Sackett's Harbour.