And I further declare and make known that such persons, of suitable condition, will be received into the armed service of the United States, to garrison forts, positions, stations, and other places, and to man vessels of all sorts in said service. –Emancipation Proclamation,

Abraham Lincoln

What is Lincoln declaring in this excerpt?

Enslaved workers fleeing the South may find refuge at military forts and outposts.
Slaves on the run will need to check into US military stations before relocating north.
Liberated persons will be required to join the US military.
Liberated persons are welcome to join the US military.