The company was founded as the
Dundalk and Enniskillen Railway (D&ER) by the '''''' (
8 & 9 Vict. c. xcvi), and opened the first section of its line, from to , in 1849. In Dundalk the D&ER line crossed the
Dublin and Belfast Junction Railway main line, which was completed between and its own separate station in the same year. With further authority from the '''''' (
15 & 16 Vict. c. xli), the D&ER extended westwards, reaching in 1854, In 1859 the D&ER reached where it connected with the
Londonderry and Enniskillen Railway (L&ER). This gave the D&ER a direct route between Dundalk and . In 1862 the INW opened a branch from southwards to . In the same year the company renamed itself the
Irish North Western Railway. In 1863 the
Ulster Railway reached Clones where it made a junction with the INW. In 1868 the
Enniskillen and Bundoran Railway opened between and , and contracted the INW to operate its line. In 1876 the INW merged with the
Northern Railway of Ireland and the Ulster Railway to form the
Great Northern Railway. ==After merger==