[BroJoeK]

Auntie Dem: "So if the civil war wasn’t about slavery, what was the Emancipation Proclamation about?
If slavery was to last forever why did Lincoln free all the inventory?"

DiogenesLamp: "Self interest....
"...By destroying slavery, they took away the economic power the people of the South would have used to fight back against them economically.
It impoverished the wealthy people and put them into circumstances where they had no choice but to continue trade with the North and the usage of it's goods and services, or they would simply become destitute."

That's total nonsense, for the following reasons:

Economically -- by 1870 US cotton production had returned to 1860 levels and by 1890 was double 1860 levels, so the South was not permanently impoverished.

Politically, in 1860, Republicans were the anti-slavery party -- anti-slavery is the reason there were Republicans replacing the old Whigs who were mostly not anti-slavery.
Morally, Republicans opposed slavery on religious & natural philosophy grounds (as had our Founders) as well as on economic and political grounds.

Militarily, even in 1861, Republicans understood that civil war would mean emancipating Confederate slaves -- since slavery was the cause of secession & war, abolition was necessary to prevent that happening again.

So, by 1862, emancipation had become a matter of moral, economic, political and military necessity for Lincoln's Republicans.

DiogenesLamp: "And giving former slaves the right to vote, knowing full well and absolutely that every single one of those votes would support the Republican party, it gave them political power to further insure their continued control of the government and thereby access to the riches the government would provide from their manipulation of it."

None of that happened.
Instead,

1. In 1874 Democrats, including Southern Democrats, won majority in the House of Representatives.

2. In 1876 Democrats won enough votes to force an election compromise in which the Republican became president at the price of removing Union troops from the South.

3. In 1878 Democrats won both houses of Congress and Republicans effectively abandoned the South to Democrats.

4. In 1880 Democrats -- with the South voting solidly --narrowly lost the Presidency.

5. In 1884 the Solid South elected a Democrat president.

This is the House of Representatives election of 1878, in which the Solid Democrat South elected majorities in both houses of Congress.
Blue = Democrats, Red = Republicans, shades = mixed.

[FLT-bird]

Militarily, even in 1861, Republicans understood that civil war would mean emancipating Confederate slaves -- since slavery was the cause of secession & war, abolition was necessary to prevent that happening again. So, by 1862, emancipation had become a matter of moral, economic, political and military necessity for Lincoln's Republicans.

False. Slavery was not the cause of secession and war. The EP was issued to:

1) Hopefully foment slave uprisings in the South which would cause chaos, carnage and economic devastation. and Make it far more politically difficult for European countries which had already abolished slavery (Britain and France) to back the CSA.