Does the OP lack access to search engines?
Hope that is not the case, and just that ignorance of the history of Juneteenth is cause for the ignorance of this OP.
"ignorance = lack of knowledge - being unaware of information
The Smithsonian has the info:
"Juneteenth marks our country’s second independence day. Although it has long celebrated in the African American community, this monumental event remains largely unknown to most Americans."
"The historical legacy of Juneteenth shows the value of never giving up hope in uncertain times. The National Museum of African American History and Culture is a community space where this spirit of hope lives on. A place where historical events like Juneteenth are shared and new stories with equal urgency are told."
Juneteenth is an often overlooked event in our nation’s history. On June 19, 1865, Union troops freed enslaved African Americans in Galveston Bay and across Texas some two and a half years after President Abraham Lincoln signed the Emancipation Proclamation.
nmaahc.si.edu