Which preposition to use with fewness

of Occurrences 22%

On account of the fewness of the men accompanying him they thought when he entered the camp that he was on a peaceful errand.

in Occurrences 1%

The fanaticism which actuated the Knights in their determination to destroy the infidel made them formidable enemies, despite their fewness in number.

Which preposition to use with  fewness