Sylvester Horton Rosecrans was born in Homer, Ohio, son of Crandall Rosecrans and Jemima (Hopkins) Rosecrans. On his father's side he was descended from Harmon Rosenkrans who emigrated from Norway to New Amsterdam about 1657. His mother was a descendant of Stephen Hopkins of Rhode Island, a signer of the Declaration of Independence.
In 1845, while a student in Kenyon College, Sylvester, influenced by the conversion of his brother William Starke Rosecrans to Catholicism and the instructions of Rev. J. B. Lamy, also entered the Catholic Church. He then transferred from Kenyon to St. John's College, Fordham, N. Y. , from which he was graduated a year later. He studied theology at Mount St. Mary's Seminary of the West (Cincinnati) and at the Pontifical Urbaniana University at Rome, where he was awarded a doctorate in divinity.
Rosecrans was ordained a priest on July 16, 1852. As a curate at St. Thomas' Church and at the cathedral in Cincinnati, as a teacher and finally rector of the collegiate department of the archdiocesan seminary, and as associate-editor with Father Edward Purcell of the Catholic Telegraph, Father Rosecrans won local renown and the favor of Archbishop Purcell, at whose suggestion he was named titular bishop of Pompeiopolis and coadjutor of Cincinnati by Pope Pius IX.
Although consecrated by Purcell, March 25, 1862, he humbly continued to teach for two years and published a small volume, The Divinity of Christ (1866). As the brother of General Rosecrans he attracted wide attention during the Civil War, and seconded the bold patriotism of his ordinary, for which he was severely criticized by the antiwar editor of the powerful New York Freeman's Journal.
A man of spirit, he showed courage in 1865 when he was wounded by burglars on his refusal to surrender a church collection. In 1867 he was given the pastorate of St. Patrick's Church, Columbus, in preparation for his elevation to the new see of Columbus (Mar. 3, 1868). He died at the age of 51.
During Rosecrans's tenure of ten years, there was a marked growth in the diocese because of the heavy Irish and German immigration. In addition to about forty churches, he built St. Joseph's Cathedral; established the Catholic Columbian in 1875, to which he himself was a regular contributor; fostered religious confraternities, especially much-needed temperance societies; instituted St. Aloysius Seminary (1871); and, through the various religious communities which he encouraged to enter the diocese, promoted a number of convents, monasteries, and orphanages.
