Complex sentence: Quakers were some of the first to value women as important ministers and to campaign for women's rights; they became leaders in the anti-slavery movement, and were among the first to pioneer humane treatment for the mentally ill and for prisoners.
Split into simpler sentences: Quakers were some of the first to value women as important ministers and to campaign for women's rights. They became leaders in the anti-slavery movement, and were among the first to pioneer humane treatment for the mentally ill and for prisoners.