Buoyed by the news that the British have easily taken Fort Mackinac and that Hull is hesitant to advance on Amherstburg from his position at Sandwich, Brock leaves York to direct operations on the Detroit front. Prior to his arrival, he learns that Hull has retreated back to Detroit. Brock interprets this as evidence of the American general's weakness of command - a weakness Brock will exploit and then attack.
The British begin an artillery barrage of Fort Detroit on August 15, after Hull refuses to surrender. Though the cannonade lasts well into the night, little physical damage is done to either side. Inside Fort Detroit, however, Hull's state of mind is quickly deteriorating. Hull is terrified of being attacked by Tecumseh's tribesmen. His worst nightmare comes true as 500 First Nations warriors cross the Detroit River under the cover of darkness and surround the fort. As day breaks, the Americans realize that the warriors and 700 of Brock's troops are boldly marching on their position. From across the river, British guns are firing a deadly stream of fire into the overcrowded American stronghold. The atmosphere in the fort is descending into chaos. Native war cries fill the air and have a devastating effect on Hull. His mind reeling with visions of a bloody massacre of soldiers and civilians, Hull surrenders despite vehement disagreement from his officers and troops. The British take the fort without a fight.
Isaac Brock becomes a hero throughout the British Empire and his army secures a windfall of bounty and supplies. The victory at Detroit provides much needed momentum to the British cause in Upper Canada. Besides inspiring confidence amongst the militia it convinces many neutral native tribes to join Tecumseh's alliance. For the Americans it is a tremendous setback. This is not the easy war the War Hawks had promised.
The Battle of Detroit, also known as the Battle of Fort Detroit or the Surrender of Fort Detroit, was a humiliating loss for the Americans early in the war. The battle cost the Americans an entire army and brought to a halt the planned invasion of Canada, which was an essential part of the American war strategy.
Gen. Isaac Brock commanded all British forces in Upper Canada. Opposing him at Detroit was American Gen. William Hull, an aging veteran of the American Revolutionary War. When Fort Mackinac fell to the British early in 1812, Brock's confidence was strengthened to launch a campaign against Detroit, even though his forces were far smaller than Hull's and consisted mostly of militia. Brock was able to gather some 100 regulars and 300 militia, and personally left his headquarters at York to lead the attack against Hull. Hull, with 2,500 troops, had plans to launch a campaign against the British forces at Fort Amherstburg.
Upon hearing of the loss of Fort Mackinac and Brock's bold movement towards him, Hull retreated into Fort Detroit. Some of Hull's officers disagreed with this retreat, and secretly discussed removing him from command.
In early August, Brock arrived outside Detroit with an additional 200 indian warriors under the command of the Shawnee Chief Tecumseh. On August 15, Brock began bombarding the Americans inside the fort. In an attempt to deceive the Americans into believing there were more British than there actually were, Brock instituted a number of simple changes in dicipline. For instance, troops were told to light individual fires, instead of one fire per unit, thereby creating the illusion of a much larger army. Likewise his troops were marched in plain sight of the defenses then quickly marched off and duck behind entrenchments, where they would join the front of the cue again. The same was done for meals, where the line would dump their beans into a hidden pot, then walk to the front to pick them up again where they could be seen. To the observing U.S. forces, it appeared long lines of troops were waiting just out of their sight. He also gave his militia uniforms of regular army soldiers to make Hull believe most of the British force were regulars. Tecumseh's warriors did likewise, and made loud warcries.
Brock sent a message to Hull that included an unmistakable threat of massacre:
"The force at my disposal authorizes me to require of you the immediate surrender of Fort Detroit. It is far from my intention to join in a war of extermination, but you must be aware, that the numerous body of Indians who have attached themselves to my troops, will be beyond control the moment the contest commences…"
Brock's plan worked better than he believed it would. Hull despaired of holding out against a force of seemingly thousands of British regulars, and, hearing the Indian warcries, began to fear an orgy. Women and children, including his own daughter and grandchild, still resided within the Fort. Against the advice of his subordinates, Hull hoisted a white flag of surrender. He sent messengers to Brock asking 3 days to agree on terms of surrender. Brock replied he would allow him 3 hours. Hull surrendered his entire force along with 39 cannon and 2,500 muskets. Two large detachments in the area were even surrendered.
The surrender of Hull's army was a great victory for the British, since it completely thwarted the U.S. strategy of invading the Canadian provinces. The British gained an important post on American territory and won control over Michigan and the Detroit region for most of the war. The Americans would not regain the upper hand on this front until the American victory at the Battle of Lake Erie and the invasion of Canada launched by Hull's successor, Gen. William H. Harrison.
Brock emerged as a hero and Tecumseh's influence was strengthened. Brock left Col. Henry Procter in command at Detroit and went to repulse an American invasion at the Battle of Queenston Heights, which would claim the general's life. Tecumseh was killed at the Battle of the Thames. Hull was court martialed and sentenced to death for his actions at Detroit; because of his service in the American Revolution, he was pardoned by President James Madison.