Peter Arnold Karthaus (1765-1840) established a mercantile business in Baltimore trading with Germany, Holland, France, and the Caribbean. He was born in Hamburg, Germany, and emigrated to Baltimore. During the War of 1812, he operated at least ten vessels as privateers under letters of marque. However, he remained a silent partner in these ventures.

Karthaus was also a pioneer in opening up the trade of the valley of the West Branch of the Susquehanna River and attempting to direct it to Baltimore. Around 1810 to 1815 he purchased large tracts of land in Clearfield County, Pennsylvania, particularly around the junction of Little Moshannon Creek and the West Branch, where the town of Karthaus was eventually built. Agents were sent to open the property and ship coal down the Susquehanna to Baltimore in flatboats called "arks." Arks were a common form of conveyance in the Susquehanna watershed and were carried downstream during high water with cargoes of coal, grain, and other commodities. At their destination, they were broken up for lumber, and the crews walked or hitched rides back upstream. While Karthaus's experiments in trying to smelt iron ore with the local coal failed, he continued to ship coal downriver, at least until the opening of the West Branch Division of the Pennsylvania Canal.