Black people were essential to the abolitionist movement, given that the struggle was over their human right to personal liberty. Therefore, it was key that black people who had been slaves tell their stories by speaking at abolitionist rallies and writing for abolitionist newspapers.
Frederick Douglass was the most prominent of these black abolitionists. He formed a relationship with the well-known Boston abolitionist William Lloyd Garrison, who published the newspaper, The Liberator. Douglass was inspired by both Garrison's newspaper, as well as the publisher's support, to start his own abolitionist newspaper, The North Star. This move is significant because it was the first instance in which a black person who had experienced slavery seized some agency over telling his story and that of other black people who had suffered slavery.
Many white abolitionists opposed slavery based on moral principles. Some had never had any contact with the slave system. Many white female abolitionists tended to compare their lowly statuses as women to those of slaves. Thus, the abolitionist movement became a catalyst for the suffrage movement. However, black female abolitionists were keen to distinguish between the experiences of white women and those of black women in slavery. White women who were the wives of plantation owners could not own property and often acquired no education; however, they were complicit in the slave system, which bestowed them with some power.
Sarah Parker Remond, an internationally-renowned abolitionist and lecturer from a prominent black family based in Salem, Massachusetts, described how black women often experienced rape at the hands of their masters. Sojourner Truth, in her famous speech, "Ain't I a Woman?," delivered at the Women's Convention in Akron, Ohio in 1851, explained how notions about femininity oppressed both black and white women. I mention all of this to illustrate how black abolitionists were especially instrumental in showing how slavery was not merely a black problem or a Southern problem but a problem that compromised the nation and that degraded everyone connected to the system of bondage.
In regard to the colonization movement, not all black people were opposed to it. For example, the abolitionist and physician Martin Delany, who worked with Frederick Douglass on The North Star, supported colonization as a solution to black people finding more opportunity and better lives outside of the oppressive conditions in the United States. Many other black people, however, opposed the colonization movement, which was initially supported by Abraham Lincoln. They believed that they had earned the right to full citizenship. Similarly, William Lloyd Garrison also spoke out against the plan for colonization, believing that it merely allowed white people to avoid confronting their culpability. He also saw it as a plot for slaveholders to perpetuate slavery abroad.