Why did Frederick Douglass give his speech, "What to the Slave is the Fourth of July?"?

Frederick Douglass was invited to give a speech on the meaning of the Fourth of July, and he gladly accepted so that he could present his own views. By the time he gave his now-famous speech in 1852, Douglass was already a noted abolitionist. In speaking to an anti-slavery organization, he knew that the audience would contain many prominent Americans, including President Fillmore. Douglass made sure to include the meaning of “liberty,” encapsulated in the July 4th declaration, for all Americans. In particular, he focused on the hypocrisy of the founding fathers’s words and their subsequent deployment, as many Americans were decidedly unfree. Slavery, Douglass noted, constituted the most fundamental contradiction between word and deed.
Douglass took pains to distinguish between the rhetoric espoused in the past, showing its degree of success in the lives of white Americans but relative lack of value for black Americans. He addresses some contemporary policy decisions—notably the 1850 Compromise—that would deliberately allow slavery to continue into the future. Arguing that it is morally and legally indefensible, Douglass predicts that slavery will inevitably be abolished.