Irish nationalists found nobody willing to help them; that is also what drove Ho Chi Minh (and many other colonized peoples) to communism. While many came to the US and served it well, they always knew the US and UK were mates; while the US offered opportunity, it was never going to press England to leave Ireland.
Dont you believe it. The “special relationship” between the US and the UK was only sparked in WW1, and only really blossomed in the middle of WW2. In the 1920’s the US Navy was convinced it would be at war with the British Empire before the end of the decade. It was only the rise of Hitler that saw that thinking begin to recede.
Prior to 1910 anglo-american relations were decidedly cool.