When it comes to synonyms for the phrase "be vanquished," there are a number of different options available. Some synonyms for this phrase might include "be conquered," "be defeated," "be overcome," or "be routed." Other possibilities might include "be overpowered," "be humbled," "be subdued," or "be quelled." Ultimately, the best synonym to use will depend on the context in which the phrase is being used, as well as the desired tone and emphasis. Some synonyms may be more forceful or dramatic than others, while others may be more subtle or understated. Regardless of which synonym is used, however, the overall meaning is generally the same: to be defeated or overcome by someone or something else.