Crusade is a term that accepts several meanings. The concept is used to designate the military expeditions (made for a religious purpose) that the Christians of the West have carried out between the end of the 11th century and the 13th century with the aim of regaining control of the Holy places occupied at the time by Muslims.
As the soldiers wore a cross on his chest, this type of campaign was known as the crusade. The Crusades were carried out mainly against Muslims, but there were also clashes against Jews, Orthodox Christians and the Mongols, among others.
Historians believe that the Crusades were both in the defence of a religious belief and expansionist zeal of European nobility, who wanted to control the trade in Asian.
This is the Grégoire VII Pope who idealized a union of Christian countries to fight against Islam, regarded as a common enemy. Another Pope (that is, urban II) took over to start the first crusade.
On the other hand, means crusade campaign to create a movement of opinion, or any difficult to accomplish. Examples: "the Uruguayan team failed in his crusade in the Aztec tradition", "crusade of the father ended a week later when his child has finally been accepted in the new school", "solidarity crusade has already collected $ 14 million", "I want to participate in the crusade against cancer.