Sentence:  First of all, and probably greatest of all in view of most present-day writers, they were "unhyphenated!" This is indeed wonderful! And again, most wonderful! <WSD>Unhyphenated</WSD>! So interesting a fact as this, and one so eminently desirable, invites most critical investigation, for the very breath of suggestion insinuates at once that "hyphenism" and "Americanism" are by the very nature of things contradictory, and that "hyphenism" must needs be on a par with, if not exactly the same as, treason. We are therefore very much interested in the new fact that Pennsylvania's glory lies in the giving of "unhyphenated" Americans to the new nation born of the travails of the Revolution. 
Meaning of the word marked with <WSD> tags:  Of people, belonging to a single ethnicity or nationality: names for multi-ethnic/multi-nationality groups generally require a hyphen to connect the names being combined.