By 1790 the abolition movement was gaining ground in Canada and the ill intent of slavery was evidenced by an incident involving a slave woman being violently abused by her slave owner on her way to being sold in the United States. The Act Against Slavery of 1793 legislated the gradual abolition of slavery: no slaves could be imported; slaves already in the province would remain enslaved until death, no new slaves could be brought into Upper Canada, and children born to female slaves would be slaves but must be freed at age 25. The act remained in force until 1833 when the British Parliament's Slavery Abolition Act finally abolished slavery in all parts of the British Empire. Historian Marcel Trudel has documented 4,092 recorded slaves throughout Canadian history, of which 2,692 were Aboriginal people, owned by the French, and 1,400 blacks owned by the British, together owned by approximately 1,400 masters. Trudel also noted 31 marriages took place between French colonists and Aboriginal slaves. 1775–1815 British agents worked to make the First Nations into military allies of the British, providing supplies, weapons, and encouragement. During the American Revolutionary War (1775–1783) most of the tribes supported the British. In 1779, the Americans launched a campaign to burn the villages of the Iroquois in New York State. The refugees fled to Fort Niagara and other British posts, with some remaining permanently in Canada. Although the British ceded the Old Northwest to the United States in the Treaty of Paris in 1783, it kept fortifications and trading posts in the region until 1795. The British then evacuated American territory, but operated trading posts in British territory, providing weapons and encouragement to tribes that were resisting American expansion into such areas as Ohio, Indiana, Michigan, Illinois and Wisconsin. Officially, the British agents discouraged any warlike activities or raids on American settlements, but the Americans became increasingly angered, and this became one of the causes of the War of 1812. In the war, the great majority of First Nations supported the British, and many fought under the aegis of Tecumseh. But Tecumseh died in battle in 1813 and the Indian coalition collapsed. The British had long wished to create a neutral Indian state in the American Old Northwest, and made this demand as late as 1814 at the peace negotiations at Ghent. The Americans rejected the idea, the British dropped it, and Britain's Indian