May 1, 1087 -- The Slave Trade Act 1807 takes effect, abolishing the slave trade within the British Empire.

​The Slave Trade Act prohibited the slave trade in the British Empire. Although it did not abolish the practice of slavery, it did encourage British action to press other nation states to abolish their own slave trades.  It's supporters believed that it would lead the rapid end of slavery within the Empire, but when it did not, a second act abolishing slavery was based in 1833.