The Emancipation Proclamation legally freed the slaves in states "in rebellion", but, as a practical matter, slavery for the 3.5million black people in the South effectively ended in each area when Union armies arrived. The last Confederate slaves were freed on June 19, 1865, celebrated as the modern holiday of Juneteenth. Slaves in the border states and those in some former Confederate territory occupied before the Emancipation Proclamation were freed by state action or (on December 6, 1865) by the Thirteenth Amendment. The Emancipation Proclamation enabled African Americans, both free blacks and escaped slaves, to join the Union Army. About 190,000 volunteered, further enhancing the numerical advantage the Union armies enjoyed over the Confederates, who did not dare emulate the equivalent manpower source for fear of undermining the legitimacy of slavery.