The slave trade ended because loads of people campaigned against it.
Some people stopped using sugar, because so many slaves worked on the sugar plantations.
But we want to know what you think is important to support today.
Is there an issue that bothers you so much you'd campaign against it?
Perhaps it's animal testing, fox hunting or poverty? Or maybe it's something else?
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
I think that climate change is important and that we should all do as much as we can to stop it like recycling more.
Alex, 10, Wrexham
Child Cruelty should stop. I support the NSPCC and their work.
Katie, 12, Wales
I think that slavery still happens around the world and I think that it is so cruel and I think that racism still exists and is really out of order!
We are in the 21st century - poverty needs to end because people are still suffering.
Andrea, 9, Bedford
I wish that there was more that I could do to persuade people to protect the environment and care for the world.
Apryl, 9, Essex
I would stand up against racism because even though slavery in the UK has been eliminated, alot of racism still exists.
Lyssa, 11, Stewarton
I think animal cruelty because all animals deserve a loving, caring life however they behave!
Emma, 11, Poole
I would ban fox hunting.
Anthony, 11, London
Domestic violence shouldn't happened because it doesn't just affect the person it happens too.
Kimberley, 13, Nottingham
I think we should all be taught about climate change as it is a serious thing we have to put up with.
Megan, 13, Scotland
I would help children in Africa where there is AIDS, they can't go to school, instead they work. And if we are upset then most of us just turn to our parents but who can the children who don't have anyone turn to?!
Holly, 9, Cheshire
I would stand up for the law that might change about kids in school because it could be that you have to stay at school until you're 18 - that is not fair!
Yasmin, 13, Lichfield
I am so happy that the slave trade is over because my great
Granddad was a slave.
I think fox hunting should be banned because it's an innocent animal that is being killed just for fun - Ban fox hunting!
Chris, 12, Crewe
If I had the power I would stop all wars and try to make peace in the Middle East and Africa. I would also stop child poverty.
Amran, 10, Manchester
I would stop terrorist attacks because thousands of people die every year. They should be stopped and put in prison for the rest of their lives.
Tom, 9, Bristol
Child cruelty should be stopped. We cannot fight back.
Louise, 11, Salisbury
I think poverty in Africa should be stopped, because so many people are dying because of AIDS.
Robert, 5, Edinburgh
I think more should be done for the families who suffer from the Iraq war.
Sarah, 9, Dorchester
I think slavery is wrong, everybody has their own rights, treat people with respect, We're all the same, we're all HUMAN!!!
Mollie, 12, Kidderminster
I would campaign or even protest against poverty in Africa, because it makes me feel sad to see all those children my age without anything!
Funmi, 13, Kent
My first action would be to stop all kinds of animal cruelty and start a conservation organisation. Every creature has a right to live on earth- not just mankind. I also think we need to start looking at how other people live and not only ourselves.
Ellie, 11, Mifield
I would stop global warming as we all are damaging our planet and making it unsafe to live in.
Becky, 11, Bristol
I would like to stand up for anti-racism.
Carla, 11, Newcastle
If I had all the money in the world, I would give all the homeless people a house, build loads more prisons for people being racist as I hate it, and give money to the poor so they can buy food and water for their families.
Ellie, 10, Runcorn
I would like to campaign against people being racist to each other because wherever you study or work you will always have someone with a different background from you.
Zara, 10, Peterborough
I would stop animal testing as every living thing has a right to live and enjoy life free not in cages.
Rebecca, 11, Bristol
I would stop cruelty to animals, fox hunting, poverty, help global warming, help extinct animals and children in Africa. Phew!
Lauren, 11, London
The main things I'd stand up for are world peace, global warming and against animal cruelty in all places.
Arllen, 11, Worthing
There are so many things that need to be campaigned against and stopped, it's impossible to pick one. Animal cruelty of any kind, poverty and racism are all high on the list.
I would stand up for pretty much anything that involves stopping violence and cruelty!!!!!
Ella, 13, London
I would campaign against animal testing. It is not fair on the animals that suffer for us.
Rosie, 11, Reading
I would like to make poverty history, stop racism and stop cruelty to animals. These are my main things I would stand up for.
Estelle, 10, Sutton
I would campaign against animal rights activists and against the hunting ban. I would also stand up for animal testing.
Eris, 13, Felixstowe
I would campaign because the government wants everyone to have ID cards. I think this is wrong because it will mean we have less freedom and the police will have all our details on record.
Emily, 13, Reading
I would campaign against animal hunting of all kinds. It's inhumane and wrong.
Toby, 13, London
I would like to campaign about a lot of things but my main one is to make poverty history!
Ella, 11, Sheffield
I would stand up for my friends.
I would like to campaign about racism in football. I think more should be done to stop it.
Joshua, 10, Luton