The marriage Schartz-Mergen took place in Bissen. You can view the original record at. https://familysearch.org/pal:/MM9.3.1/TH-266-11557-60246-21?cc=1709358&wc=M9M6-26L:1433988830 Here is the basic information: marriage 27 Feb 1842 in Bissen Jean-Pierre Schartz, farmer, born in Bissen 8 Nov 1813 son of the late Nicholas Schartz (died 18 Apr 1837 in Bissen) and Margaret Majerius (died 30 Apr 1829 Bissen), paternal grandson of Theodor Schartz ( died Neunhausen 19 Mar 1830) and of Elisabeth Sch...[illegible, paper fold] (died Neunhausen 26 fructidor Year XIII of the Republic) and maternal grandson [this mentioned in margin] of Theodor Majerius (died Bissen 27 Aug 1818) and of Catherine Zenner (died 29 Jul 1812) married to Madelien Mergen, born in Bissen 23 Aug 1821, duaghter of Philippe Margen and Catherine Prinz, both living in Bissen.
Note. 26 fructidor year XIII is a date of the Republican Calendar introduced at the French Revolution. It corresponds to the 13 Sep 1805 of the Gregorian Calendar, which we use today.