Sentence:  14 of America's best chess players are wielding kings, queens and their chessboard servants in a silent but brutal war. . . . "It's a mental war, it's a <WSD>war of nerves</WSD>, of logic, or reasoning, of being a good fighter," said Walter Browne. 
Meaning of the word marked with <WSD> tags:  A situation in which opposed parties refrain from direct conflict but maintain a tense, contentious relationship in which each uses annoyances or intimidating psychological tactics to attempt to dishearten and unnerve the other.