Julius Hermann Kroehl (in German, Kröhl) (1820 – September 9, 1867) was a German American inventor and engineer. He invented and built the first submarine able to dive and resurface on its own, the Sub Marine Explorer, technically advanced for its era. His achievements in architecture, civil and mechanical engineering were also significant. Origins and personal life Early life Julius Hermann Kröhl was born 1820 in Memel, East Prussia (today Klaipėda in Lithuania). His family moved to Berlin, Kingdom of Prussia around 1828. He arrived in New York City on 29 July 1844 on board the Fairfield. While residing in New York City, he became an American citizen on October 26, 1849, formally renouncing any loyalty to the King of Prussia and taking on the duties of American citizenship. During his civilian employment with the United States Navy, he was referred to as "captain." Using the honorific title of "captain" was usually indicative of holding an officer's commission in foreign army or having served as an officer in a volunteer militia or fire company. In his letter of introduction to Brigadier General Jacob Lauman, his qualifications were described as having served "in the artillery abroad." Family His father was Jacob Kroehl. He was a merchant in Memel. From 1829 to 1833, the family residence was listed as Hausvogteiplatz 11, Berlin, suggesting that the family relocated to the Prussian capitol around that time. His mother, Johann Philipine Dorothea, later immigrated to the United States in 1848, but as the wife of a British merchant, John Heanes. His brother Henry (1819–1890) left to the U.S. in 1838. He had established himself as a merchant, with a business in New York City, and later resided in Asbury Park, New Jersey, after 1870. He was a partner with Otto Dill, until he died in 1861. Henry was married to the former Cornelia Rogers Turfler. Their bodies were buried at Green-Wood Cemetery. Passenger lists and passport records suggest that Henry made a few trips to Germany throughout his life. No other siblings have been identified to this article at this time. William John Kroehl (1816–1879) resided in England from 1836 through the remainder of his life. UK marriage records show a different father; his citizenship petition showed that he came from Memel, and is likely a cousin. He was naturalised a British citizen on 23 January 1849. Otto Sackersdorff (1820–1879) also resided in New York