How the Crusades Worked

An angel leading the Crusaders to Jerusalem
Gustave Dore/The Bridgeman Art Library/Getty Images

The control of Jerusalem and the Holy Lands. Wars fought to defend religious beliefs. Conflicts between Islam and the Western world. These all read like topics ripped from today's headlines, but they were actually the issues of the day in the 11th century, when the pope called for Christians to rise up and go to the Crusades.

The Crusades were a series of battles, beginning in 1095 and lasting several generations, designed to gain the Holy Land for the Christians. When we think about the Crusades today, we are heavily influenced by historians' varied interpretations of the battles. We may picture knights righteously galloping off to protect the land connected with the life of Christ. Or, we may envision murderous barbarians who caused blood to gush like a river through the streets of Jerusalem. Some may connect the Crusades with greedy popes thirsty for power and land, and cast judgment on the Catholic Church for condoning such violence.


It's even tempting to look at the players of the Crusades and draw conclusions about conflicts in the Middle East today. President George W. Bush sparked criticism and outrage, when, in the days following the attacks of September 11, he spoke of "this crusade, this war on terrorism." Critics claimed his use of the word "crusade" implied a conflict between civilizations and religions, rather than against terrorists. And some pointed out that it was like rubbing salt in the wound of Muslims left scarred by the Crusades.

If we're going to understand how the Crusades worked, though, we're going to have to ditch our modern-day baggage. Imagine you're living in Europe at the end of the 1000s. You've never left your small town, yet you hear stories that average people like yourself are experiencing unspeakable atrocities in other lands. Your ears are ringing with these horrific tales when your religious leader announces that war against this enemy will provide you the greatest of spiritual rewards -- redemption of sin and entry into heaven. All you have to do is raise the money for your trip, walk 3,000 miles and fight an unknown foe that has military techniques you've never seen before.

Would you heed that call? Read on to find out more about the people who did, and the culture that influenced such carnage in the Holy Land.

Setting the Scene for the Crusades

The world at the time of the Crusades

At the end of the 11th century, Western Europe was generally a primitive, backward place, in comparison to the Middle East's more sophisticated society. Feudalism had been the main form of government for several generations, and strong monarchs and central governments were just beginning to reemerge. You can read more about Feudalism in How Knights Work.

The church was the main source of European unity at the time. For people living in Europe, life was marked by a sincere love of God that was expressed openly and often. Faith permeated every aspect of daily life, but so did fear. A lunar eclipse might be seen as a sign of God's favor, while a lightning storm was seen as a symbol of his wrath. People were scared of the ever-present temptation of sin, and they depended on the church's teachings to get to heaven.


Pilgrimages became popular practice at this time. After all, what could be more holy than standing where Christ once stood? Priests sometimes even prescribed pilgrimages as a way to perform a penance, or the act of repenting for one's sin. The city of Jerusalem had been under Muslim control since 638, but until the late 1000's, that wasn't an immense concern for the Christian world. Pilgrims were still allowed to make their journey to the Holy Land to see the site of the crucifixion and resurrection of Jesus Christ.

In the Middle East, power was shared by three entities:

  • the Byzantine Empire, or the eastern half of the Roman Empire
  • the orthodox Sunni Muslims in control of Iran, Iraq and Syria
  • the Shia Muslims in Egypt.

The Byzantine Empire was shaken by the rise of the Seljuk Turks. The Seljuk Turks took lands that included almost all of Asia Minor from Byzantine hands. And they showed no signs of slowing toward the Byzantine capitol of Constantinople. The Seljuk Turks also began to obstruct Christians in their pilgrimages to Jerusalem.

Alexius I, the emperor of the Byzantine Empire, wanted to restore Byzantine control over Asia Minor and northern Syria, but he couldn't do it by himself. Feudalism in Western Europe had led to the rise of knights, so he knew where he could tap military strength. He reached out to the leader of the Western church: Pope Urban II.

Alexius I sent representatives to the pope to tell him the Turks were mutilating and torturing pilgrims in the Holy Lands. He reported that the Turks were also raiding and conquering the Holy Lands and that his fellow Christians should rise up to fight for God.

Pope Urban II had several political reasons to endorse the Crusades. For one, it was a chance to mend the relationship between the Greek church in the east and the Latin church in the west. The two churches had been divided over doctrinal and theological issues since the Great Schism of 1054. It was also a move to cement the power of the papacy, which was on the rise due to the Gregorian Reform movement of the mid-1000s. Additionally, the rise of feudalism had created a lot of knights, but the knights were restless and fighting random battles to entertain themselves; a war would be a convenient outlet for their energies.

But how could the pope call for war, when the church was known for promoting peace? Learn more about his persuasive logic on the next page.

The Call for the First Crusade

Peter the Hermit preaching the Crusades to the people
English School/ The Bridgeman Art Library/Getty Images

In 1095, Pope Urban II sent out the word that he was going to preach at the Council of Clermont, a meeting of priests and laymen. Other church business had already been conducted by the time Urban II took the pulpit, including a ratification of the "Peace of God" canon, which was the result of a peace movement that had been developing in the church, particularly in France. The canon called for a truce in the name of God to stop warfare and assaults against defenseless beings.

When Pope Urban II spoke, the crowd was so large that the sermon was moved outside. Several versions of the speech circulate, but most report the pope's accounts of torture, decapitation and forced circumcision the pilgrims were suffering in the Holy Land. He called upon the warrior knights to stop disturbing the peace at home and turn energy to the holy cause of helping the East.


Then Urban II played the trump card for Christians: he announced that recovering Jerusalem could substitute for a journey of penance. Such a promise incited the audience -- a group of individuals horrified of hell and desperate for the redemption of sin. "God wills it! God wills it!" they chanted. They were going to war.

But wait: How could the Council of Clermont incorporate both a call for peace and a call for war? To the church and its followers, the two calls were essentially one and the same. War would ensure peace, would relieve the suffering of the Eastern Christians. The pope and his people viewed the war as defensive, because the pilgrims and Eastern Christians were under attack.

Preparations began at once. Pope Urban II decreed that soldiers fighting for God would be marked with the sign of the cross. Ceremonies were held in which knights took vows and took the sign of the cross to wear in battle. Then the knights raised funds for their trip by mortgaging property and liquidating assets. Serving as a knight was not cheap, and the cost of service could sometimes be five to six times as much as a knight's income.

Both Urban and Alexius, however, got a little more than they bargained for. The two men had thought only the knights and trained military would join the cause; that was, after all, their job. However, Urban's preaching inspired more than just its target audience. Entire families started marching to Jerusalem immediately in what was known as the Peasants' Crusade.

The Peasants' Crusade was led by charismatic preacher Peter the Hermit. The poor were able to mobilize quickly because they didn't have any reason to stay and they didn't bother with fundraising. Instead, a mob with no means to attain food and supplies headed out, and inevitably wound up causing the problems one would expect from an unruly, hungry mob. In Hungary, they rioted over a pair of shoes, which resulted in hundreds of Hungarians being killed. The peasants pillaged towns and the countryside, killing anyone who got in their way, including Christians. They stole lumber to build boats and stripped lead from the roofs of churches.

When the peasants reached Constantinople, Alexius I tried to persuade them to hold off until more organized branches of the army could arrive. But the peasants were ready to prove themselves to God and marched anyway to Nicea. A ragtag army on foot with no armor was a rather easy target for the Turks; most of the peasants were slaughtered easily. The Peasants' Crusade was helpful to the Crusaders in one regard, though: After easily defeating the peasants, the sultan Kilij Arslan was unconcerned when he heard that more armies were coming.

What happened when the armies arrived? Find out on the next page, when we look at the bloody battles of the First Crusade.

The First Crusade

The Crusaders and their siege weapons
Gustave Dore/The Bridgeman Art Library/Getty Images

The Crusading forces were mostly French, and they set off for Constantinople in August 1096. In June of 1097, the first meeting between the Crusaders and the Turks took place at Nicea. The Crusaders sieged Nicea and held off Turkish relief armies. The Turks hung on for a month, even as the decapitated heads of Turkish corpses were flung at them. But when the Byzantine forces arrived, the Turks surrendered.

The siege at Nicea, while successful for the Crusaders, gave the Crusaders a sense of respect for their enemy. The Muslim armies possessed superior military heritage; they had manuals for war and better equipment -- spears, swords, daggers, and bows that could be shot from both long and short range. The European knights, however, were used to fighting in formations with lances and swords, and the cavalry's spears and swords were crude. The superior Muslim archery would eventually drive the Crusaders to develop heavier knight armor and the crossbow.


The Battle of Dorylauem educated the Crusaders on Muslim military bite. The battle took place as the armies were headed for Antioch. While the Crusaders camped at Dorylaeum, the Turks attacked with darts, javelins, and arrows shot from long range. As they assaulted their enemy, the Turks screamed, whistled and drummed, which added a sense of confusion and panic to the battle. Most of the Crusaders were foot soldiers -- easily cut down by the fire. The knights were tougher to kill because of their armor. But the knights were trained for organized charges with their lances. So, they didn't know how to react to a showering of arrows.

The Turks were able to stay out of range, but were finally forced to flee when Crusader reinforcements, who had been camping a short distance away, showed up. The Crusaders continued the march to Antioch.

The siege on Antioch, a city surrounded by walls and towers, lasted about eight months. Many died from starvation and disease. One of the leaders of the Crusades finally struck up a deal with a disgruntled Turk, who allowed the armies to climb over a section of the walls while the city slept. The Crusaders took the city, but they disagreed over how it should be ruled, which slowed their attempt to reach their final destination: Jerusalem.

If the Crusaders' war tactics and weaponry were so weak, then how did they eventually take hold of Jerusalem? Find out on the next page.

Siege of Jerusalem

The Crusaders march around Jerusalem.
Jean Victor Schnetz/The Bridgeman Art Gallery/Getty Images

Although their exact numbers aren't known, a weakened Crusading army showed up at the walled city of Jerusalem. In addition to battle, disease and hunger had taken its toll on the soldiers, who were so thirsty at times they had killed their horses to drink the blood. The governor of Jerusalem had the advantage: he cut off the Crusaders' water supply by poisoning and blocking the outside wells, and he had the time and supplies to strengthen the towers of the city.

The Crusaders took strategic positions at the walls, but things seemed hopeless until a priest came forward and said he'd had a vision of how to achieve victory: the Crusaders should fast and march barefoot around the city. The pious Crusaders took up the task, marching while the Muslims jeered at them from behind the walls. They stopped at the Mount of Olives for a stirring sermon that lifted their spirits.


After that, things looked up for the Crusaders (and down for the Muslims). Reinforcements arrived with food and supplies -- the supplies needed to build siege weapons. What were siege weapons? Giant towers on wheels, scaling ladders, catapults, and battering rams (to open the gates), were all siege weapons. Once they were built, those towers began moving against the city's walls.

Not to be outdone, the Muslims catapulted out fire bombs, known as "Greek fire," from within the city. Greek fire was launched in pottery that shattered the fire everywhere, or in rags with nails that embedded into the walls of the tower and set it ablaze. Bales of hay soaked with oil and wax were aimed at the towers as well, but the Crusaders had nailed animal hides soaked in vinegar to the towers to repel the fire.

Finally, one of the siege towers secured a bridge into the city and took control of a portion of the wall. With control of the wall, scaling ladders were used to enter the city, which occurred right about noon on a Friday. The Crusaders noted that they were entering Jerusalem at the time of Christ's death.

The taking of Jerusalem by the Crusaders
Emile Signol/The Bridgeman Art Library/Getty Images

Some of the Muslims took shelter in the temple area and surrendered to Crusading forces, while others continued to fight from the Tower of David, a citadel in the middle of the city. Finally, a Crusading general, concerned that he was missing out on the looting that had already begun in Jerusalem, offered to stop fighting if the Muslims would surrender the tower to him. These Muslims agreed and were allowed to leave the city, making them the only ones to survive the siege of Jerusalem.

The Crusaders spent the next night and day killing Muslims, even ones who had been granted terms of surrender. They cut open the Muslims' stomachs, after one soldier said the Muslims had swallowed their own gold. The Jews, who had sought refuge in their synagogue, were burned alive when the Crusaders set fire to it. Witness accounts talk of blood running in the streets, and body parts carpeting the city -- that is, of course, until all those body parts were burned.

This kind of slaughter strikes our modern-day sensibilities as savage and barbarous. But the Crusaders felt they were in good favor with God. They had been charged to cleanse Jerusalem from the contagion of non-Christian forces and had succeeded. The city where Christ died finally was, in the Crusaders' view, strictly Christian.

The First Crusade wasn't the only Crusade, and the Holy Land did not remain in Christian power forever. In spite of their differences in objectives and strategy, the First Crusade and the others that followed it had three things in common -- religion, politics and siege warfare. Read on to learn how each of these contributed to the later Crusades.

Religion in the Crusades

St. Bernard of Clairvaux preaching the Second Crusade
Emile Signol/The Bridgeman Art Gallery/Getty Images

After the First Crusade, popes continued to call for Crusades; their blessing was seen as essential. After all, these battles were perceived as "God's will." Many of the Crusades would begin with a goal to reach the Holy Land, but would break down because of politics and warfare failure. Regardless, religion was always the primary trigger for a crusade.

Though religion always played a part, the perceived threat to the church evolved. The first Crusade focused solely on ridding the Holy Land of Muslim forces. But later Crusades addressed other threats to the church -- even threats at home. The popes began to use crusades to combat any perceived threat against the Catholic Church.


Take, for example, the Albigensian Crusade (1209-1229). This crusade battled heresy within the church. In the French city of Albi, a heresy called Catharism was extremely popular. Catharism held that the world was caught between spiritual and material matters, and that all material matters should be shunned. It held that Jesus Christ was God, but was never man. Cathars believed that the Eucharist was blasphemous and that the Church perverted Christ's word.

The Church sent Crusaders to fight the perceived heresy. The Crusade was fairly popular because it took place much closer to home. However, despite many Cather killings, the Cathar heresy was still present in the region for the next century.

The spirit of the Crusade was not isolated to popes and knights. The common people also caught the fever -- wanting to express their own religious devotion to the cause. The Children's Crusade (1212) wasn't an actual crusade, but is a term used to describe popular uprisings similar to the Peasants Crusade in 1096.

In one such uprising, a young man named Nicholas set out for the Holy Land. He believed that the Mediterranean Sea would dry up when he reached it, which would allow him easy access to the Middle East. As he went from town to town, all sorts of people joined his march. Another boy named Stephen also began marching; he went to the king of France, claiming he had a message for the king from Jesus Christ. He also attracted a large group of followers. Both children, though, were unable to free the Holy Land. The king told Stephen to go home, and Nicholas was foiled when the Mediterranean Sea did not part for him.

In addition to religious fervor, politics played its part in the Crusades. We'll look at how on the next page.

Politics in the Crusades

A map of the Crusader States established after the First Crusade.

The political impact of the Crusades affected everything from nations' relationships with one another to the creation of entirely new political states. During the First Crusade, Alexius I had asked all crusading generals to swear an oath that any recovered land be returned to the Byzantine Empire. But when Alexius I was discovered retreating from the siege at Antioch, the Crusaders lost respect for the man and were not inclined to fulfill their promises.

As a result, four Crusader States were formed to be ruled by the West: the kingdom of Jerusalem, the principality of Antioch, the county of Edessa, and the county of Tripoli. The new Crusader States lacked strong leadership, however, and they were easily taken back by the Muslims.


In 1144, the Crusader State Edessa was captured, which prompted a call for the Second Crusade (1145-1148). At this point, kings and monarchs from the West began to get involved, which placed a political slant on what transpired during the Second Crusade. When Louis VII of France arrived in Antioch to prepare to take back the Holy Land, he felt the rulers of the Crusader States were undermining the holy purpose of the Crusades. There was some difficulty deciding what city to attack. The armies, meeting at Jerusalem, hesitantly decided to attack Damascus, even though its Muslim emperor was generally friendly with the Crusader States. Damascus was seen as a threat to Jerusalem because of its close proximity. The siege was a failure, however, as we'll see on the next page.

The Second Crusade also laid groundwork for poor political relations between the Byzantine Empire and the West. The Byzantines were none too thrilled about the returning Crusaders, remembering their poor behavior during the First Crusade. The emperor had developed some treaties with the Turks -- a decision that made the West distrust the Byzantines. Louis VII blamed the failure of the Second Crusade on the Byzantines' failure to provide supplies. This feeling unfortunately provided the groundwork for the Fourth Crusade.

The Battle of Zadar in 1202
Hulton Archive/Getty Images

The Fourth Crusade (1202-1204) was political from the outset. The armies were to meet in Venice, and then proceed to the Holy Land. However, when the French army arrived, it was much smaller than anticipated, which angered Venice. The French had contracted with Venice for ships and provisions. But the small army didn't need that many supplies, nor could it afford them. The Venetians had already invested a great deal in the French. To get its money's worth, the Venetians ordered that the French take the city of Zadar. The city of Zadar (located in today's Croatia) was a Christian city, but it had been rebelling against Venetian rule. Pope Innocent III strongly disagreed with this strategy, and many knights refused to take part, but Zadar was captured in 1202.

After capturing Zadar, the Crusaders headed toward Constantinople, the capitol of the Byzantine Empire. They planned to take part in a plot to give the throne to a young boy named Alexius Angelus, son of Isaac II, who had been deposed as Byzantine Emperor in 1195. Alexius Angelus promised to help the Crusaders take the Holy Land. Relations had eroded between the East and West, and the Crusaders were eager to win back their ally.

The Crusaders attacked Constantinople, setting fire to a corner of the city, and installed Alexius Angelus as emperor. Alexius Angelus proved to be unpopular and was toppled in another coup. The Crusaders, angry that they hadn't gotten the help they'd been promised, saw this as yet another sign that the Byzantine Empire stood in their way. The Crusaders declared war on Constantinople, and set about looting the richest city in Christendom. They sacked the city for three days, defiling holy places, destroying and stealing valuables, raping women, and cementing the schism between East and West.

Politics played its most successful part in the Sixth Crusade (1228-1229), when Frederick II of Germany managed, through diplomacy and negotiation, to secure Jerusalem for the Christians. This would last for ten years.

Next, we'll learn more about the Crusades' intriguing siege warfare tactics. How were catapults, towers and moats used to attack a walled city? Find out on the next page.

Siege Warfare in the Crusades

The crusader in battle
Francis Phillip Stephanoff/The Bridgeman Art Library/Getty Images

Because of the scale of the Crusades' battles and because Muslim warfare was so much more advanced, the Crusaders had to develop new war tactics. These siege warfare tactics were sometimes successful -- but in other cases, they failed completely. For example, in the Second Crusade, the crusader methods to attack Damascus were disastrous. The Crusaders could find no safe place from which to launch an attack. The western side of the city was wooded, and the enemy Turks hid in the trees. The eastern side had no trees, which left the Crusaders out in the open. After only four days, the Crusaders retreated in failure.

The Third Crusade (1189-1192) was marked by the Siege of Acre, which lasted almost two years. The Third Crusade began when the Muslim warrior Saladin drove a force of Crusaders into the hills at the Battle of Hattin. Saladin went on to conquer Jerusalem in 1187. Guy of Lusignan, who had been king of Jerusalem, headed to the city of Acre with a small army, hoping to rebuild his political fortunes.


Acre was surrounded by battlements and had a pair of huge towers, and even Saladin doubted Guy would have much success. However, Guy's soldiers pitched their camp outside the city and dug ditches and moats around it. In the meantime, reinforcements from the West began arriving. The ships brought both fresh soldiers and the needed supplies to build siege weapons. The Crusaders built massive siege towers, four stories high -- as high as the walls of Acre.

When the towers were ready, the Crusaders battled from them. Muslim archers battled back from the tops of the walls of the city. Meanwhile, foot soldiers piled rocks and brush into Acre's moat; the filled moat would provide a foundation for the towers pull up alongside the walls of Acre. The Muslims threw boulders and pots of Greek fire from inside the city, but the Crusaders had again reinforced the walls of their towers. The Crusaders also tried unsuccessfully to destroy one of the city's towers by ramming vessels loaded with combustibles into it. But due to shifting wind, only the ships were damaged.

The siege picked up again when Richard I of England and Phillip II of France arrived in 1191. The French tunneled under one of the towers and then set the supporting timbers on fire, while the rest of the army bombarded the city from outside with siege engines, such as catapults. The French named one of their catapult's "God's Own Sling." Saladin was unable to rescue Acre, and the city surrendered in 1191. The Crusaders' ability to cut off Saladin's reinforcements, while receiving reinforcements of their own, ensured the success of the siege.

Although Richard I marched to Jerusalem, his army had dwindled, and he was eager to return to England to address political matters at home. He made a treaty with Saladin that gave the Muslims control of Jerusalem, but allowed Christian pilgrims access.

So, other than the development of new siege warfare methods, what kind of impression did all this brutality and fighting leave on the world? In the next section, we'll take a look at the impacts of the Crusades.

Impacts of Crusades

The returning crusader
Carl Friedrich Lessing/ The Bridgeman Art Library/Getty Images

After all this fighting, you'd think that the Crusades would have left immense impacts on the world. However, historians today attribute very little of what happened next in Europe or the Middle East to the Crusades [source: Madden]. They generally believe that while the Crusades were significant at the time, they didn't really change the face of Europe or the Middle East any more than those faces would have naturally changed and evolved.

Economic impacts were felt in Europe; the Crusades caused a decrease in European wealth, as Crusaders had invested substantially to go to the Holy Lands. Some positive impacts were felt in Italy; although they had been trading with the East prior to the Crusades, they essentially dominated the entire Mediterranean by the end of them.


One of the more lasting impacts was on the relationship between the Greek and Latin churches. The bitter relations throughout the Crusades, culminating in the sack of Constantinople in the Fourth Crusade, put an end to any sense of possible reconciliation between the East and West.

Essentially, though, it seems that fighting between Western Europeans and Muslims simply stopped, and each turned their attentions to other matters [source: Madden]. In Europe, religion was no longer a central identifying force. And as it emerged from the Dark Ages, the Crusades were seen as nothing more than the hysteria of the time.

Each succeeding generation has presented its own version of the story of the Crusades. And those versions inform how we view the Crusades today. The Romantics idealized the Middle Ages, pointing to the chivalry of knights and the piety of the people. During the rise of French nationalism in the 1800's, the French highlighted the Crusades as the country's first attempt to bring western civilization to the world. By the time of World War I, the Crusades were used like propaganda -- they showed how a campaign can be used to meet a morally-just goal. Marxists saw the Crusades as an attempt to address a shortage of resources in Europe and stripped the Crusaders of any religious motivations. History books cemented the reputation of Crusaders as barbarians. And modern-day Christians have called for the pope to apologize for the horrors committed during the Crusades.

Muslims at the time of the Crusades were fighting wars with many groups and saw Christians as just another group of infidels. The first Arabic history of the Crusades was not written until 1899, and it was a constructed memory -- taught to the Muslims by the European colonialists. In the 1950's, when the idea of colonialism and imperialism was discredited by the West, that also discredited the Crusades [source: Madden].

Obviously, this article doesn't even scratch the surface of all that transpired during the Crusades. Links to the works of scholars who have devoted their lives to studying and writing about the Crusades, as well as some related How Stuff Works articles, are on the next page.

Lots More Information

Related HowStuffWorks Articles

More Great Links


  • "Crusades." Encyclopedia Britannica. 2008. Encyclopedia Brittanica Online Library Edition. (Jan. 28, 2008)
  • Czech, Kenneth P. "Third Crusade: Siege of Acre." Originally published in the August 2001 issue o f Military History Magazine. The History Net. (Jan. 28, 2008)
  • Ford, Peter. "Europe Cringes at Bush 'Crusade' Against Terrorists. The Christian Science Monitor, Sept. 19, 2001. (Jan. 28, 2008) (Jan. 28, 2008)
  • Gore, Terry L. "First Crusade: Battle of Dorylaeum." The History Net. (Jan. 28, 2008)
  • Knox, E.L. Skip. "The Crusades." (Jan. 28, 2008)
  • Various lectures available at
  • Madden, Thomas F. "The New Concise History of the Crusades." Rowman & Littlefield Publishers, 2006.
  • McFall, J. Arthur. "First Crusade: People's Crusade." Originally published in the February 1998 issues of Military History Magazine. The History Net. (Jan 28, 2008)
  • McFall, J. Arthur. "First Crusade: Siege of Jerusalem." Originally published in the June 1999 issues of Military History Magazine. The History Net. (Jan 28, 2008)
  • Nicolle, David. "Essential Histories: The Crusades." Fitzroy Dearborn Publishers, 2001.
  • "Templar." Encyclopedia Britannica. 2008. Encyclopedia Britannica Online Library Edition. (Feb 5, 2008)
  • Tyerman, Christopher. "Fighting for Christendom: Holy War and the Crusades." Oxford University Press, 2004.