"All the Crusades met the criteria of just wars. They came about in reaction attacks against Christians or their Church. The First Crusade was called in 1095 in response to the recent Turkish conquest of Christian Asia Minor, as well as the much earlier Arab conquest of the Christian-held Holy Land. The second was called in response to the Muslim conquest of Edessa in 1144. The third was called in response to the Muslim conquest of Jerusalem and most other Christian lands in the Levant in 1187.This take on the Crusades is completely new to me, especially the remarks on the cost of crusading. Now that I think about it, the expensiveness of a long journey should perhaps have been obvious. The cost of plane tickets today ought to have brought that notion quickly to mind. Also, I'm sure my middle school social studies textbooks mentioned the historical context for the launching of the Crusades, rather than listing them as completely isolated events. Nonetheless, as long as I have known about the Crusades, I have had the impression that I as a Christian ought to be ashamed of them, that the Crusaders were acting completely wrongheadedly and destructively, and that I ought to utterly disown them. When my agnostic friend demanded an accounting for the misdeeds of the church throughout the ages, and listed the Crusades as the spearhead for the critique, my response was not to correct her impression of history, but to avert my eyes and chatter about how Christians continue to make mistakes and how their actions do not reliably reflect the religion--or better yet, faith--as a whole (a line of argument which is valid only up to a point, because if adherence to a religion doesn't actually change the way you live, then what's the point??)
In each case, the faithful went to war to defend Christians, to punish the attackers, and to right terrible wrongs. As Riley-Smith has written elsewhere, crusading was seen as an act of love--specifically the love of God and of neighbor. By pushing back Muslim aggression and restoring Eastern Christianity, the Crusaders were--at great peril to themselves--imitating the Good Samaritan. [...]
The cost of crusading was staggering. Without financial assistance, only the wealthy could afford to embark on a Crusade. Many noble families impoverished themselves by crusading.
Historians have long known that the image of a Crusader as an adventurer seeking his fortune is exactly backward. The vast majority of Crusaders returned home as soon as they had fulfilled their vow. [...] One is hard pressed to name a single returning Crusader who broke even, let alone made a profit on the journey. And those who returned were the lucky ones. [...] One can never understand the Crusades without understanding their penitentiary character."
From Thomas F. Madden's article "Inventing the Crusades" in First Things (June/July 2009, Number 194; pp. 41-44).
But having read this, I can breathe a sigh of relief. It makes sense that Catholic powers would send aid to their allies, even though this pluralism-obsessed day and age don't customarily consider religious ties to be the foundation for political alliances. It is understandable that the promise of forgiveness for sins one was acutely aware of would motivate going to war. It is hard to argue that any war is free from atrocities, whether the war itself is justified or not.
To my mind, the idea of an indulgence is completely wrong-headed, and the notion that fighting and killing people could earn your forgiveness is a distortion of Biblical doctrine. Still, it's good to know that the Crusades, whether actually justified or not, are at least justifiable.