From just war to holy war to crusade

How we go
from a just war
to a holy war
and then to a crusade?

1) In the 11th century, military expeditions were essentially an act of solidarity by the West towards its brothers in the East who were threatened by Turkish expansion: a war justified by Realpolitik, a lesser evil necessary for geostrategic reasons.

2) As the violence escalated, it became a holy war: by dying in battle, you became martyrs for the Christian faith that you were protecting against Islam.

3) The term crusade appears only at the end to reinforce the justification of the violence: killing and being killed became meritorious; it ensured the salvation of your soul.

10 (21 – 11) lessons from the 11th century for the 21st century?

In World War 2, “never in his history has man competed so much with the devil nor given so many lessons to hell” (André Malraux).