strike a blow

verb2

1. •
   To hit; to successfully land a hit.

   • His opponent danced and dodged so nimbly that he couldn’t strike a blow.
2. •
   (figurative) To do something to support or defend (for) or to hinder or harm (at / against) something.

   • The Supreme Court ruling struck a blow for gender equality.
   • It is hoped that the new vaccine will strike a blow against the spread of tuberculosis.