The "Idealistic" view...
We were/are taught by these historians that the Republicans (i.e. the North) were against slavery and for national economic reforms. Under the leadership of Abraham Lincoln, the slaves were freed and the Union saved, and we all lived happily ever after.
Realistic view...
The Republicans were a percentage of the Northern voting bloc in 1860, about 50-55%, and were against the expansion of slavery, into territories they wished to populate with Northern whites- only; not the abolishment of the institution where it existed. In the early years of the Republican Party the platform had two priorities- helping black Americans and modernizing the Northern economy. By 1860-61 the primary Republican platform was the Northern economy under the power and theory of "nationalism"; federal lawmakers passed legislation for internal improvements, higher tariffs, a national banking system, a uniform currency, a homestead act, a transcontinental railroad, and admitted new "free states", (i.e. black free states) into the union; the majority of these laws passed before any issues to slavery question were addressed- like the abolition of slavery. By the 1870s, after this terrible war, and with the same leadership, the Republicans abandoned the ex-slaves they had "freed". By now Republicans main platform was to support the Northern economy by changing currency, federal subsidies to corporations, regressive taxation, and the use of troops to suppress strikers and relocate Indians; i.e. helping the rich Northerners get richer. The Republican changes to the U.S. Government were the catalyst in the rise of monopolies and robber barons in the late 19th Century.
The North was not all abolitionists, the freedom to own and use slaves was not opposed where it was practiced but the institution of slavery was opposed by the majority of Northerners where they lived and worked. If 45% of Northerners did not vote for Lincoln, then it would be justified to say the same percentage and maybe more approved of slavery in the new territories, and good many more approved of slavery where it already existed, well into the 1860s.
The North's claim to a higher moral ground over the South is questionable when the "idealistic" view of the causes and goals of the war are removed and replaced with the realities of history.
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David Upton