It is Gordon Granger that started Juneteenth. Juneteenth is known to be the oldest national holiday that is being celebrated right now in most states of the United States. This is a holiday that is meant to celebrate the freedom of the slaves from their masters. This happened on June 19 of 1865, which explains why the name of this is Juneteenth. Gordon Granger was the person who arrived in Texas and made the announcement.
This was made official and it was put on paper. However, some slaves were not immediately released at that time because the war was still ongoing then. Some slaves had to spend two more years in captivity before being released. Some of them were not able to survive.