Ah, they were at that, Kate, but they were so much more. When one considers the immediate history surrounding the Crusades, one will discover that 'cities back' are key words.
You see, the Roman Empire split into two, leaving the Roman and Byzantine sections. The Byzantine Empire became stronger while Rome was weakened by war, poor rulers and corruption, as well as barbarians. Eventually, Rome fell, leaving the Byzantine Empire as a remaining power with a plethora of Arabic enemies. Throughout its history, it had perpatually been fending off Islam and Arabic people. In the Byzantine-Arab wars (starting at 634 AD), the Christian Byzantium lost a excessive territory to the Arabs.
Under the rulers Rashidan and Umuyyad, the Islamic faction consumed (by warfare) what had previously been Christian or peaceful African land. Any defence that could be thrown together fell easily before the rampaging Moslems. North Africa, Persia, Sindh (India) all were lost by 736AD.
In all of this time, Constantinople held out, which, naturally, aggravated the aggressive Moslem Armies.
However, the Moslems weren't finished. No, from there, they proceeded into Christian Europe. They took Italy, the Caucauses, the Iberian Peninsula (Spain and Portugal), the Pyrenees and even parts of the Bulgarian Empire. The Moslems, in fact, advanced into what was then France and the German States. Only Charles Martel had an army large enough to prevent them from proceeding, and, miraculously, he did prevent the Islams from consuming all of Continental Europe, earning the nickname, 'The Hammer'.
This is all wrapped up by 950. Only small heros and forces stood to face the triumphant Muslims in those conquered countries, as can be seen by the Spanish folklore hero 'El Cid', and his small guerrila army of which bravely fought the Moor despots.
Maybe, once realizing the surrounding conquests, one can see why the Christians finally united into one army in order to gain back what had been theirs and to protect the Holy Land.
There is one last item that must be mentioned of the background of the first Crusade. Jerusalem fell from the Byzantine Empire. 3,000 Christian Pilgrims were slaughtered, and the Christian churches were desecrated.
Are the Christian forces not justified in taking back that of which is rightfully theirs? When people state the the Crusades were a bloodbath "Instigated by Christianity". or a 'Foolhardy religious conflict', it irritates me to no extent. That person obviously does not realize how close Europe came to being completely subjugated.
It is true that the Armies of Europe, once running rampant, committed many deeds they should not have while flying the Christian standard. However, as a whole, the Christians were justified and thus not 'religious fanatics fought by religious fanatics against comparatively peaceful Moslems. ' Thus, if you ever hear this, remember who actually instigated the fight. Remember that there hasn't been 'more evil in the world instigated in religion', which is then immediately drawn to the Crusades as an attempt at an argument.
And also remember, that, while our soldiers performed some deeds they were often later ashamed of, brutal and cruel warfare was regular in the Medievil Ages - consider what the Moslems did to the People's Crusade.
That's all for now. Cheers