Juneteenth is a great name for a Holiday.
Abraham Lincoln released the Emancipation Proclamation on Jan 1, 1893.
Southern Democrats were doing everything that they could to resist emancipation; so there was a need to impose local rules in each of the states.
You are correct to notice that something extremely strange is going on.
Interestingly, one will develop a completely different idea about what happened in the United States if people looked at the political parties.
Hint: Abraham Lincoln and General Gordon were Republicans.
What was the other party doing.
Another interesting thing. Abraham Lincoln wanted reconciliation after the Civil War. As a grand gesture he appointed a Democrat named Andrew Johnson as the Vice President.
Johnson and Southern Democrats did some nasty things to regain power after the Civil War.
The whole story becomes different when one looks at the two parties.