Monsingnor Michael Francis Cassidy, of County Cavan, Ireland, became pastor of St. Patrick's, O'Neill, in July, 1866. Under his direction, the beautiful church, the rectory and St. Mary's Academy were built. He served St. Patrick's for 47 years.

Monsignor John G. McNamara, a native Nebraskan, became pastor of St. Patrick's in March, 1934. He served through the years of depression and World War II. First as "Father Mac" and then as Monsignor, he devoted the remaining years of his life to the parish and the school.

Monsignor Timothy O'Sullivan, born and educated in County Kerry, Ireland, continued the long history of commitment to the parish and school. During his tenure the school became the parish responsibility and, in 1965, the old Academy was destroted by fire. with foresight and dedication, he undertook the building of a new high school, convent and grade school.