519 anti-slavery petitions were handed to parliament in 1792, with 390,000 signatures on one.
Ex-slaves like Olaudah Equiano wrote about the horrors of the slave trade.
William Wilberforce tried 12 times in 15 years to abolish the slave trade.
Thomas Clarkson collected evidence about slavery.
Hannah Moore wrote poems and books against slavery.
Economic factors: Britain made £1 million (10%) a year from sugar tax, but profits decreased with cheaper sugar from Brazil.
Arguments that free slaves would work harder and generate more tax revenue.
Slave rebellions demonstrated the intelligence and strength of enslaved people.