They wanted new states to be free from slavery, so they would not have to compete with slave labor.

VOA: special.2009.04.30

And in fact in one with the girl describing her side, she several times emphasizes this need for protection, need to be free from being torn down from people around them.

事实上像一个女孩子表达的那样，她好几次强调了需要保护的愿望，需要逃离那些打倒她的东西,逃离身边的人们。

麻省理工公开课 - 媒体、教育、市场课程节选

I believe anyone would be perfectly right to interfere with you, so far as to free those you wickedly hold in slavery.

VOA: special.2009.07.02

And it voted that Oregon should be free territory, with slavery illegal.

VOA: special.2009.03.05

Iranian attendance at the events, Ros-Lehtinen said, could be equated to fraternizing with the oppressors of people in Iran who yearn to live free.

VOA: standard.2009.06.23