And the manner in which that was done was a farce. All the people in the conquered states were not allowed to vote. This was a denial of the rights of the people and the 13th amendment was rubber stamped by a puppet "Vichy" government.
No amendment should have been possible until the normal civil order was restored, and I am quite confident that if the actual will of the people was made manifest, the 13th amendment would never have passed.
Noooo, by April, 1865, only two Union states had not passed abolition laws: Kentucky & Delaware.
Kentucky reported ~225,000 slaves in the 1860 census (yes, I looked it up), of whom it's estimated around 40,000 remained to be freed by the 1865 13th Amendment.
The rest had been freed, or freed themselves and 24,000 had served in the Union Army.
Delaware's slave population had been falling for decades and in 1860 was reported as ~1,800 of whom ~1,000 remained in 1865 to be freed by the 13th Amendment.
So here are the key dates in US abolition laws:
DiogenesLamp: "And the manner in which that was done was a farce.
All the people in the conquered states were not allowed to vote. "
All the people in the conquered states who declared allegiance to the United States, including some former slaves, were allowed to vote.
Confederates, having declared themselves non-citizens, were temporarily disenfranchised.
DiogenesLamp: "No amendment should have been possible until the normal civil order was restored, and I am quite confident that if the actual will of the people was made manifest, the 13th amendment would never have passed."
Normal civil order was restored when Confederates surrendered, primarily in April 1865.
Those loyal to the Union did vote to ratify the 13th Amendment.
After the disputed 1876 election, former Confederates returned to political power and effectively nullified the 13th, 14th & 15th Amendments for most of the next 100 years.
But, slowly, times do change and even Mississippi's 1865 rejection of the 13th Amendment was reversed in 1995, Mississippi's ratification confirmed in 2013.