1. [n]  a series of actions advancing a principle or tending toward a particular end; "he supported populist campaigns"; "they worked in the cause of world peace"; "the team was ready for a drive toward the pennant"; "the movement to end slavery"; "contributed to the war effort"
2. [n]  any of the more or less continuous military expeditions in the 11-13th centuries when Christian powers of Europe tried to recapture the Holy Land from the Muslims
3. [v]  go on a crusade; fight a holy war
4. [v]  exert oneself continuously, vigorously, or obtrusively to gain an end or engage in a crusade for a certain cause or person; be an advocate for; "The liberal party pushed for reforms"; "She is crusading for women's rights"; "The Dean is pushing for his favorite candidate"

Crusade
Atkinson follows the unfolding of the Persian Gulf War from the first night to the final day, providing vivid accounts of bombing runs and White House strategy sessions, firefights, and bitter interservice conflicts. Atkinson portrays the allied campaign against Saddam Hussein as one that transformed the very nature of modern warfare.

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1. \Cru*sade"\ (kr?-s?d"), n. [F. croisade, fr. Pr.
   crozada, or Sp cruzada, or It. crociata, from a verb
   signifying to take the cross, mark one's self with a cross,
   fr. L. crux cross; or possibly taken into English directly
   fr. Pr. Cf. {Croisade}, {Crosado}, and see {Cross}.]
   1. Any one of the military expeditions undertaken by
      Christian powers, in the 11th, 12th, and 13th centuries,
      for the recovery of the Holy Land from the Mohammedans.
   2. Any enterprise undertaken with zeal and enthusiasm; as, a
      crusade against intemperance.
   3. A Portuguese coin. See {Crusado}.
   

2. \Cru*sade"\, v. i. [imp. & p. p. {Crusaded}; p. pr. &
   vb. n. {Crusading}.]
   To engage in a crusade; to attack in a zealous or hot-headed
   manner. ``Cease crusading against sense.'' --M. Green.