Sentence:  Our youth, now, emboldened with his success, resolved to push the matter farther, and ventured even to beg her recommendation of him to her father's service; <WSD>protesting</WSD> that he thought him one of the honestest fellows in the country, and extremely well qualified for the place of a gamekeeper, which luckily then happened to be vacant. 
Meaning of the word marked with <WSD> tags:  To affirm (something).