Studied art in Nüremberg and Munich (Doctor of Divinity, University of the South). Worked at engraving until 1848. Came to the United States, 1848.
Had studio, 1857-1861, Madison, New Jersey, and Brooklyn, New New York
After 1861 in Westerly, Rhode Island. Painted many scriptural and other pieces, and animals.
After studying art in Germany at Nuremberg and Munich, he practiced engraving until 1848, in which year he came to the United States and taught for a time in Newark, New Jersey. They eventually had four children. In 1857 he was elected an associate of the National Academy of Design.
In 1857 he moved to Madison, New Jersey, where he painted Lament of the Fallen Spirits and Redemption.
About this time, he was invited to assist in preparing new decorations for the capitol in Washington. His painting Rock of Ages became enormously popular and was reproduced in millions of photographs and chromolithographs for sale both in the United States and England.
During the American Civil War, Oertel accompanied the Army of Virginia under General Burnside for several months in 1862. His Virginia Turnpike and other landscapes were the fruit of this military experience.
He then confined himself almost entirely to the domain of Christian art, and painted pictures that he presented to churches in Glen Cove, New York, New York City, Washington, District of Columbia, North Carolina, and elsewhere.
He had charge of two parishes in North Carolina (in Lenoir) until 1876. He moved around a great deal as a priest and spent time in North Carolina, Florida, Tennessee, Saint Louis, Washington District of Columbia, Maryland and Virginia. Oertel was an instructor of art at Washington University in Street Louis, in 1889-1891.
He spent the last 18 years of his life in a town near Washington District of Columbia, where he made many religious paintings and wood carvings.
He painted a series of four large pictures entitled The Plan of Redemption which he presented to Sewanee (the University of the South in Tennessee). His last major work came in 1906-1907 when he created the paintings and designed the new woodwork for the altarpiece of the Cathedral at Quincy, Illinois.
Married Julia Adelaide Torrey.