Which preposition to use with coblentz

during Occurrences 1%

The mental condition of the French emigrants at Coblentz during this summer of 1791 is nothing short of a psychological marvel.

on Occurrences 1%

So in the winter of 1790 the French fugitives congregated at Coblentz on the German frontier, persuaded that they were performing a patriotic duty in organizing an invasion of their country even should their onset be fatal to their relatives and to their King.

to Occurrences 1%

With the same view, emissaries were dispatched from the Court of Coblentz to the South of France in order, under the disguise of patriots, to preach up the most exaggerated corollaries to the theories of liberty and equality.

Which preposition to use with  coblentz