Sentence:  So the author, after seeking vainly between the editions of 1938 and 1965 a peg on which to hang his <WSD>Thermidor</WSD>, in the end gave up and labeled the Russian case "permanent revolution," without, however, explaining how this aberrant outcome of the Bolshevik fever came about. 
Meaning of the word marked with <WSD> tags:  A (counterrevolution); a (coup d'état) resembling the (Thermidorian Reaction).