noun

each of a series of medieval military expeditions made by Europeans to recover the Holy Land from the Muslims in the 11th, 12th, and 13th centuries.

the fanaticism engendered by the Crusades

verb

lead or take part in a vigorous campaign for social, political, or religious change.

he crusaded against gambling in the 1950s

campaign,fight,do battle,battle,take up arms,take up the cudgels,work,push,press,strive,struggle,agitate,lobby,champion,promote