The deadly persecution of the Scots by the English in the 17th and 18th
centuries led to a migration of over 600,000 Scots to America during that
period. Many historians believe that the bloody conflicts between the
Anglican English and the Presbyterian Scots during that period spilled over
into the American Revolution, where Scottish Americans played a large part,
and the American Civil War, where Scottish southerners figured prominently:

"There had been many conflicts between the English and the Scots over the
years, but the most significant war between England and Scotland actually
began with the Declaration of Independence issued in Philadelphia in 1776.
In order to understand Patrick Henry, you have to understand Braveheart and
vice versa. The rebellion of ‘45 under Bonnie Prince Charlie [against the
House of Hanover] ended in 1746 - a mere thirty years before hostilities
between the Scots-like Americans and the House of Hanover resumed. ...

"After the ... rule of Cromwell, Charles II persecuted the Scots viciously
during the ‘killing times.’ William III brought some relief in 1688, but
after his death, more restrictions were placed on them. In response an
enormous stream of Scots and Scots-Irish migrated to the colonies, and all
of them held a very dim view of the English. And when an enormous stream of
Scots began sailing to America, the word enormous should not be overlooked:
"After the year 1714, their ships began to cross the sea from Ulster in a
long unbroken line. For more than sixty years they continued to come. It was
the most extensive movement ever made from Europe to America before the
modern days of steamships. Often as many as 12,000 came in a single year.
... In the two years, 1773 and 1774, more than 30,000 came. A body of about
600,000 Scots was thus brought from Ulster and from Scotland to the American
colonies, making about one-fourth of our population at the time of the
Revolution.

"The impact of these immigrants on the development of the South was immense.
The War for Independence and the War Between the States must be understood
as containing an important element of the ongoing conflict between Celtic
peoples and the English - up to and including St. Andrew’s cross on the
Confederate battle flag and the rebel yell. And these immigrants were
overwhelmingly Presbyterian. When war broke out between England and America,
Peter Oliver, a Tory writing in 1781, rebuked the ‘black regiment, the
dissenting clergy,’ for fomenting the Revolution. He was referring to the
black robes worn by Presbyterian ministers. When the Americans took up the
fight with London, it was not a new war, but the continuation of an old one.
...

"At Yorktown, Washington’s colonels with one exception were Presbyterian
elders. More than half the soldiers in the Continental Army were
Presbyterians, and most of the rest were other kinds of Calvinists. The
British army specially targeted Presbyterian churches because they knew that
they were in the thick of it, and the ‘black regiment’ was effective in
supporting the war. One name for the war in England was the Presbyterian
revolt. One of the biggest controversies in the colonies before the war was
whether the king was going to appoint an Anglican archbishop over all the
colonies. The rallying cry in the American Revolution was ‘No King but
Jesus.’ ...

"One Hessian officer, writing home during the war, said, ‘Call this war by
whatever name you may, only call it not an American rebellion; it is nothing
more or less than a Scotch Irish Presbyterian rebellion.’"

–Douglas Wilson, 5 Cities that Ruled the World, Thomas Nelson, Copyright
2009 by Thomas Wilson, pp. 144 - 146