Answer:
Although this is not the holocaust, it is similar. In the transatlantic slave trade, many believed it was just the African Americans who were sold the most, but in reality, the Irish were the most enslaved and killed race in the 1900s'. Their population declined from 6 million to 400,000. The enslavers were New england, Americans, and some cubans. They were used for labor and killed. This was the most killed race in the slave trade, and they were white.
The world was going through a lot with the war efforts and freeing other slaves, not many took notice to the Irish slaves, because they were white, but had no rights.