Which preposition to use with boire

after Occurrences 1%

" Napoleon, however, must be held responsible, inasmuch as since the close of the Seven Weeks' War, he had intrigued with Austria to induce her to revenge herself by a joint attack with him upon Germany, hoping that he might win with Austria's help those concessions of territory along the Rhine, which Bismarck had peremptorily refused him as a pour-boire after Sadowa.

of Occurrences 1%

a mile) per horse, with a pour-boire of a couple of keráns to the "Shagird" at the end of the stage.

Which preposition to use with  boire