When George Bush abandoned his promised "humble foreign policy" in favor of bringing truth, justice and the American way to an ancient land that has been ruled by great conquerors for more than 3,000 years, from Shalmaneser and Sargon II to Abu Ja'far Abdallah ibn Muhammad al-Mansur and Hulagu Khan, the media was rife with references to the Crusades of medieval fame. Unfortunately, five years after the most recent fall of Baghdad, it is increasingly obvious that John McCain's promise of 100 years of occupation notwithstanding, this American Outremer is unlikely to last half as long as its nominal predecessor did.
Because the media is almost completely ignorant of military matters, it has quite understandably escaped the greater part of the American public that the short-term success of the minor reinforcing operation known dramatically as "the surge" is almost completely irrelevant. Most news analyses are day to day, and most opinion writers think only in terms of their next column, so the chances of any media figure looking beyond the next election is an exotic outlier approaching Black Swan probabilities. All the same, it's worth noting that there are distinct lessons from a previous military occupation of the Middle East that are still applicable some 1,000 years later.
    1. Public appeal
The First Crusade's stated goal of reclaiming Jerusalem was enthusiastically supported by Christendom's general public; a modern equivalent of the People's Crusade would be 700,000 American civilians voluntarily arming themselves with deer rifles and hopping aboard their jet skis and fishing boats to travel across the ocean in order to attack Iraq. (As ludicrous as this sounds, it would still probably turn out better than the historical People's Crusade did.) As it stands, there are barely 700,000 Americans who even consider the war to be the most important political issue of the day, it's amazing how pro-war drama queens have been complaining for five years about how no one realizes "we are at war." After all this time and the electoral disemboweling of the Republican House and Senate, they should realize that for the vast majority of Americans, "we" most certainly are not at war. It's just President Bush and his neo-praetorian guard.
    2. Reconquest is popular, conquest is not.
The First Crusade and the Reconquista were successful attempts to regain previously Christian land that had been lost to Islam. The Second Crusade, which was billed as the recapturing of lost Edessa but transformed into a failed attempt to conquer wealthy Muslim Damascus, required the religious salesmanship of Saint Bernard and his promise of absolution of sins to garner even a lesser level of enthusiasm. Attempts to sell the Iraqi war by comparing it with the World War II-era reconquest of Europe and the South Pacific have failed, because it's clearly a simple matter of conquest, the president's many mutating justifications notwithstanding. 
3. Conquest without colonization is short-lived
Outremer could not survive because it did not generate its own military forces but was dependent upon the constant importation of knights and men-at-arms from far-off Christendom. Considering that Britain today sent its final reserve unit, the 1st Battalion Welsh Guards, to Kosovo, means that an already overstretched "Coalition of the Willing" is soon going to find out that it does not have the resources to meet the tactical obligations that will develop, let alone the more important strategic ones.
    4. Action inspires reaction
The pre-Crusades Muslim Middle East was weak and politically divided. The external pressure unexpectedly put upon the Islamic world through the ambition of Zengi and his sons and the Christian treachery of the Second Crusade paved the way for the rise of Saladin. This is precisely why Osama bin Laden hoped to provoke a Western invasion of the Ummah; bin Laden has been dead for years, but his dream lives on and his strategy remains operative so long as the occupations of Iraq and Afghanistan remain ongoing.
    5. Faith trumps greed
The Crusader kings of the Second and later Crusades found that the farther their objectives departed from those in line with a religious motivation, the less success they achieved despite having far greater resources at their disposal than the low-ranking nobles of the First Crusade. The occupations of Iraq and Afghanistan rely on the notion that the appeal of secularism will outweigh the religious traditions of those lands; however, the explosion of Islam throughout secular post Christian Europe and the recent triumph of religious Islam over secular Islam in Turkey indicates that American military strategists are basing their plans on an empirically false foundation.
History suggests a rock-paper-scissors analogy may be helpful to understand the strategic situation, wherein secularism trumps Christianity, Islam and paganism trump secularism, and Christianity trumps Islam and paganism. Of these rival cultures, demographic trends clearly indicate that Western secularism is the weakest and most likely to be subsumed by the others. And if this analogy serves as an accurate model, then it should be obvious the only way to win the clash of civilizations in the long term will not be through a modern crusade to spread secular culture to the Levant, but rather a Christian reconquista of what was once Christendom.
Original Source