Original: It was built as the backbone of the regional fortification system , Festung Koblenz , by Prussia between 1817 and 1832 and guarded the middle Rhine region , an area that had been invaded by French troops repeatedly before .
Simplified: It was built as part of the '' Festung Koblenz '' ( Fortress Koblenz ) , by Prussia between 1817 and 1832 and guarded the middle Rhine region .