WordNet records no synonym and no antonym for reconnaissance by fire. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a method of reconnaissance in which fire is placed on a suspected enemy position in order to cause the enemy to disclose his presence by moving or returning fire
Synonyms, antonyms and the broader and narrower relations for reconnaissance by fire come from Princeton University’s WordNet. Full sources and licences.