How could slaves get out of slavery?

I know of one way but it wasn't always guaranteed. They could go on the Underground Railroad. Harriet Tubman is the founder of this. It was not a real "underground" railroad. It was a covered carriage and the slaves would hide under all the crops and things under the cover in the back. Some of them made it out and some could get caught. But that is one way they could get out of slavery.