strike a blow against (something)
To do something that contributes to something's defeat or downfall. Health officials are hoping that this latest initiative will be able to strike a blow against the obesity epidemic. Reports surfaced today that, if true, will strike a blow against the nascent campaign.
strike a blow for/against/at something
act forcefully in support of/against something (for example a belief, principle or group of people): The protest was a chance to strike a blow for freedom.The new law would strike a blow against racism.