Sentence:  To my knowledge , Lincoln <WSD>remains</WSD> the only Head of State and Commander-in-Chief who , while fighting a fearful war whose issue was in doubt , proved man enough to say this publicly - to give his foe the benefit of the fact that in all human truth there is some error , and in all our error , some truth . 
Meaning of the word marked with <WSD> tags:  be left; of persons, questions, problems, results, evidence, etc.