Hey there.
Interesting thread, but I see some items that I would address.
As a white, mixed Irish/Scottish-American, my take is that the poor Irish (as opposed to the not so poor Irish) immigrants were viewed as scum and often lured to the new world with the promise of freedom from European cultural oppression. The reality was quite different from the promises. The cost of passage was supposed to be paid for by working for no pay for a time sufficient to equal the price of passage, but then the unannounced additions of cost of living/upkeep (not to mention interest charged upon these), meant that a poor Irish immigrant would end up going ever deeper into debt. This was the other form of slavery, called indentured servitude. The problem with this is, when an Irishman just decided to head for parts unknown, there is no way to just look at him and know he is a runaway 'indentured servant'.
My understanding is that this was one of the principle problems in keeping white people as slaves in all but name, and one of the main reasons for importing blacks.
In other words, if a white IS runs away, catching him is going to be very difficult and costly (and time consuming) as he can just blend into the melting pot of European immigrants. When the Black man runs away, everyone that sees him automatically thinks runaway slave (or at least this was the prevalent point of view) and so his recapture and return is going to be much quicker and less expensive.
So, the poor Irish trash and the Black man may seem to have something in common, but this is not something that is going to bring them together.
One comment I found strange was something like "In order to fit in, the Irish started to hate on the Blacks".
Before the ACW, the Irish were the poor, despised workers. After the war, freed Black former slaves began to compete for the jobs that the Irish were relegated to, and this (to my understanding) is where the tensions began between the Irish poor and the freedmen. Competition for the lowly, badly compensated jobs that nobody else wanted, not some racial or social-acceptance ploy on the part of the Irish, just a grim situation made worse by the sudden competition for already scarce means of earning a living.
One fellow did post that a need for plentiful jobs would be likely to be a prerequisite for the premise in the OP to take place. I agree. Something would have to be drastically changed if the freedmen and Irish poor were to be something other than adversaries, IMHO.
All in all an interesting premise, and looking forward to seeing what you will come up with to overcome these obstacles.
