Series of armies sent out from Europe to

win back the Holy Land from the Moslems

Crusades.

Explanation:

The location of Christian's Holy land is extremely close to the middle Eastern territories. So, when Muslim empires tried to expanded their territory, often times the Christian Holy land fell under their control.

Some of the Groups that took control of the land chose to adopt a peaceful approach to the land and let the Christians visit the land. But the relations between Christians and Muslims weren't always peaceful, so some of the groups chose to prevent the Christians from visiting.

When such occurrence happen, European Churches often sent out armies to win back the land and use the Biblical verse as a justification. This was what they referred to as the Crusades.