Oertel painted religious subjects as well as portraits. He was born in Bavaria and studied painting and engraving in Munich. He emigrated to American in 1848, settling in Newark, New Jersey. During the next two decades he earned his way by teaching art, painting portraits, engraving banknotes and designing ceiling decorations for the House of Representative in Washington D.C. In 1871 he became a priest of the Protestant Episcopal Church and for over twenty years he served parishes in North and South Carolina, District of Columbia, Tennessee, Missouri and Maryland. His work is represented at the University of the South and in many churches, including the National Cathedral at Washington.