Re partition, here is a differnet take than Jim's.
It is brief to make it easy to challenge anything that is factually incorrect.

Most of Ireland wanted out of British rule, but Ulster wanted to stay in and was prepared to fight.
Dublin wanted to force them out, but did not have the might.
Britain wanted to force them out, but the army refused to do it.
Illiberal Jim thinks they should have been forced out.
How Jim?

Politicians can only hope to please most of the people most of the time.
They tinkered with the border so as few people as possible found themselves on the wrong side of the (open) border.
What more could they do?
Some of those who did not get their own way, stamped their feet and started executing people.
It still goes on.