The heart of U.S. Reconstruction following 1865 was to regain power in the Northern Democrat controlled States and moderate Republican States that opposed and mostly hated Abraham Lincoln and the Radical Republicans of New England. During the 1860s only people born in the New England States considered themselves as "Yankee's."
New Yorkers distrusted and largely "hated" the rude people of New England and they opposed Lincoln's war. New York State had a Democrat government and a Democrat Mayor of NYC.
New Jersey had a "moderate" Republican Governor and State government that despised Lincoln and New England.
Pennsylvania, Ohio, Indiana, Illinois, Wisconsin and Michigan had Democrat governments during Lincoln's war and had no use for any Yankee's or their unconstitutional views of government.
All of these States and New York called up their militias to kick the USA out of their States beginning in 1863.
The U.S. War Department record known as the Official Records of the War of the Rebellion said that "half of all U.S. military" were fighting in the northern States. This is virtually never taught in U.S. government sponsored schools.
When the war was over most Northerner's would not vote for a Republican and without the South ‘supporting’ Republicans (FORCED UPON US BY THEIR CARPETBAGGERS), the Party of Lincoln would have been completely finished in the United States and the destructive consequences of the War may have been lessened and the South permitted to be independent. Most Northern Democrats favored Southern independence and a less centralized federal government.
To maintain control of the central U.S. government after the War, it was more important to "Reconstruct" the Northern States than it was the defeated Southern States whose voting was easier to control with Southern whites now disenfranchised.
FIRST, Republicans had to control voting in all of the Democrat States and areas of the North, and SECOND, those Democrat voters had to identify with the winners of the War, the Republicans.
At the end of the War, Northerners did not in any way identify with the Yankee New Englander's.
Southerner's understood this and referred to New Englander's as "Yankee's" and the rest of the Northern people as "Northerner's" unless they behaved liked the poorly mannered New Englander's. This dichotomy of "Northern vs Yankee" was soon lost to Northerner's as the U.S. Reconstruction of the Northern people become more and more dominant.
The success of "U.S. Reconstruction" was nearly total in the Northern Democrat States as we see today. Northerner's (not New Englander's) who fancy themselves to be "Yankee's" with a capital "Y." Southerner's STILL consider "Yankee's" with a lower case "s" as an irreligious, vulgar, profane and sexually immoral and dishonest people, and are mildly amused at the historical ignorance of Northerner's who proudly refer to themselves as "Yankee's."
Southerner's tend to have longer historical memories which is why Southerner's still resist the ongoing Reconstruction of their culture and government.