I know all eight of my great grandparents came over from "Poland" in the late 19th century. I put Poland in quotes because at that time it didn't exist as a country. It was more of a concept kept alive by the language, the song (that would become their national anthem) and the Roman Catholic faith (to the east was Orthodox, do the west was protestant). The anthem is about their struggles to regain statehood, which they finally achieved in the aftermath of World War I.
My great-grandmother's brother was a Catholic priest. He was one of 20,000 recruited in the U.S. and Canada by Polish patriots to fight in World War I. Although Woodrow Wilson allowed the recruitment of Poles in the U.S., he did not allow the recruits to be trained in the neutral United States so they were trained at Niagara on the Lake, Ontario, by the Canadian military with funding from the French government.
As an educated man, he was given an officer's commission (colonel) and was a chaplain. He did command troops in battle though and received several decorations including the Polish
Virtuti Militari which is roughly equivalent to the Medal of Honor in the US. He returned to America in 1919. He eventually became a priest at a parish in Toronto, and later in St. Catherines, Ontario.
He is probably the most famous person from my direct genealogy, although that just means you can find brief references to him in history books about the Poles in America and Canada as well as online references. He is buried at Niagara on the Lake, alongside trainees who died of the Spanish Flu in 1917 before the army went over to Europe, in a plot that was diplomatically transferred from Canada to Poland, so he is officially buried in Polish soil. He was still talked about regularly in my family when I was young even though he died 12 years before I was born. In our family we simply referred to him as Uncle Priest.