How did African Americans try to appeal for justice during conventions

By waging a biracial assault against slavery.

Explanation:

African Americans abolitionists in the first half of the nineteenth century waged a biracial assault against slavery. Their efforts proved to be of a great effect. Abolitionists focused majorly on slavery and made it difficult to ignore. They heightened the rift that had threatened to destroy the unity, peace and stability of the nation even as early as the Constitutional Convention.

Although some Quakers were slaveholders, members of that religious group were among the earliest to protest the African slave trade, the continuous bondage of its captives, and the practice of separating enslaved family members by sale to different masters.