The son of one of the first professors of Gettysburg College, Jacobs was born in that town in 1844. He was a witness to both the Battle of Gettysburg and to Lincoln’s Gettysburg Address. He followed his father onto the faculty of Gettysburg College, after serving congregations in western Pennsylvania under William A. Passavant’s guidance. In 1883 he was appointed professor of systematic theology at the Lutheran Seminary in Philadelphia, which he also served as dean and president.
Jacobs was president of the General Council’s board of foreign missions, as well as of the American Society of Church History and the Pennsylvania German Society. Prolific as an author and translator, he served as general editor of the standard English edition of The Book of Concord. He was also a compiler of the Lutheran Cyclopedia and co-editor of the English translation of The Doctrinal Theology of the Evangelical Lutheran Church by Heinrich Schmid, which served as a standard theological textbook for more than a generation.
He served on the committee which compiled the Common Service as well as the Common Service Book. At the behest of Beale Melanchthon Schmucker, chair of the Common Service Committee, he wrote The Lutheran Movement in England, which outlined the influence of Lutheran theology and practice on the Book of Common Prayer, making the language and rhetoric of that work available as a model for English-speaking Lutherans.
Jacobs witnessed and participated in every major development in eastern Lutheranism from 1860 until his death in the 1930s. His Memoirs, written for his children and edited and annotated by his grandson, Henry Eyster Horn, is a valuable, honest, and delightful source for late 19th century Lutheran personalities and church politics.