The track was originally built by the
Frederick William Northern Railway (
Friedrich-Wilhelms-Nordbahn-Gesellschaft, FWNG) as the
Carl Railway (or
Charles Railway, ) from Kassel, the capital of the
Electorate of Hesse (
Kurhessen), to the port of
Bad Karlshafen (then called
Carlshaven, German for "Port Charles", after
Charles I, Hesse’s ruler from 1670 to 1730) on the left bank of the
Weser, one of the northernmost places in the contiguous part of Kurhessen. The first section from
Grebenstein via
Hümme to Karlshafen on the south bank of the Wesser was completed on 30 March 1848. A few months later, on 29 August 1848, the remainder of the line was completed between Kassel and Grebenstein. Soon after the completion of the line, rail transport became important for connecting with sea transport, so the
Frederick William Northern Railway started building a new line from Hofgeismar-Hümme station towards Warburg in Westphalia, under an agreement between Kurhessen and
Prussia. The small border town of Haueda was reached on 6 March 1849. Since the track in Westphalia was originally the responsibility of the
Cologne-Minden-Thuringian Connecting Railway Company (
Köln-Minden-Thüringische-Verbindungs-Eisenbahn-Gesellschaft), which in the meantime became bankrupt, it was not until 6 February 1851, that the
Royal Westphalian Railway Company (
Königlich-Westfälische Eisenbahn-Gesellschaft) completed the section of its
Hamm–Warburg line between Warburg and the border. ==Route ==