Born in County Cork, Ireland, in 1846, Patrick Henry Cronin came to the United States as an infant, and, with his family, traveled from New York to Baltimore and Ontario, Canada, before settling in the mining areas of Pennsylvania. Moving to Missouri after the Civil War, he studied medicine, served in the militia during the strikes of 1877, then spent much of the following year in Ireland. In 1882, having earned a medical degree as well as a Ph.D., he moved to Chicago,where he practiced medicine and involved himself in Irish American politics.

The Clan-na-Gael.

One of the largest Irish American political organizations, the United Brotherhood or Clan-na-Gael, was established in 1869 and espoused loyalty to Ireland and independence of the island from British rule. The estimated ten thousand members of the Clan-na-Gael were organized into local chapters, or "camps," which...