What effect did the proposed 13th Amendment have during the Civil War and what effect did it have for slaves in Union states after the conclusion of the war? None, not until passage. Why didn't the virtuous Union pass the 13th Amendment itself? They were afraid to upset the Union slave states.
Civil War began in April 1861, the first Battle of Bull Run in July.
By August 1861 slaves were running away to Union lines and Congress passed the first Confiscation Act protecting them from return.
In 1862 Congress outlawed slavery in Washington, DC, and Lincoln wrote his Emancipation Proclamation.
Congress debated various slavery related proposals and in 1863 proposed an abolition amendment, which passed the Senate in 1864 and the House in 1865.
Ratifications:
Oh, our Lost Causers claim, but Congress was way too slow, since it took them years to accomplish what was previously impossible for decades, if not centuries.
So Congress gets no credit for abolishing slavery, but only censure for taking so long to do it, our Lost Causers tell us.
Well, that's just your typical Democrat talk.
Ask any Democrat today if President Trump gets credit for 3.9% unemployment, what's the answer?
No freaking way, they say, because wages are still too low.
Well, what about the tax cuts, we ask?
Nothing but "crumbs" they say, and so it goes, on & on.
Democrats are oppressive in power, berserkers out of power, both today and 1861.
In 1830 it was nullification, in 1861 secession, today sanctuary cities & state, all just more of Democrats doing what Democrats naturally do.