Use the subject search: "Personal narratives" AND (enslaved OR slave*) in Worldcat or the main library catalog.
The Library of Congress formally uses the subject "enslaved" but some older works are still cataloged under the discontinued term "slave" or "slaves."
Do NOT limit to publication date; most of these materials have been published on compiled volumes much later, and limiting the publication date to pre 1865 will miss important works.
Using (slave* OR enslaved) as a subject with other genre types (ex. Diaries, correspondences, personal memoirs") as subjects will also yield interesting results.
For freed individuals, the best search is a Subject search for "Personal Narratives" AND "African Americans"
There will be a number of false hits, but it's worth skimming to avoid missing something important. If you really don't want to skim, try added the keyword phrase (freed* OR reconstruction)
Highlights