The historical document that called for the abolition of slavery in the British Empire was the Slavery Abolition Act of 1833. This legislation made it illegal to enslave people, effectively emancipating over 800,000 enslaved individuals in the colonies. The act was the culmination of decades of activism led by abolitionists like William Wilberforce and the broader anti-slavery movement, which highlighted the moral and humanitarian imperatives against slavery. The act not only marked a significant step toward human rights in the British Empire but also influenced other nations in their own movements towards abolition.