Sentence:  He <WSD>is</WSD> most effective in the ordinary business of the House , and in the legislative accomplishments of this session , he easily rose to great occasion - even at the height of unpleasantness and exciting legislative struggle - and as the Nation witnessed these contests , he rose , even as admitted by those who differed with him , to the proportions of a hero and a noble partisan . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)