The Second, Third, and Fourth Crusades explained

The First Crusade was fought from 1095 to 1099. It was successful in capturing Jerusalem and the surrounding area for the European forces.

Four Crusader states were set up: the Kingdom of Jerusalem, the County of Tripoli, the Principality of Antioch, and the County of Edessa.

However, the Muslim nations in the Holy Land had not been defeated. In 1144, a Muslim leader called Zengi, fought back against the crusaders and captured Edessa on the 24th of December.

Any Europeans found in the city were killed or sold as slaves.

This event made the Christians realise how precarious their situation was: they were in a foreign land surrounded by hostile forces that outnumber them.

The Crusaders states knew that they could not hold on to their territories without further help from Europe.

Following the fall of Edessa to the Muslim armies, a Second Crusade was called by Pope Eugene III in 1145.

Echoing the call of the First Crusade, the pope offered the remission for sins to any European lord or soldier who joined the military expedition.

To further encourage recruitment, the pope asked the popular French abbot, Bernard of Clairvaux, to preach on the subject.

In response to the new crusade, around 60,000 men signed up, primarily from the regions of France and Germany.

The main armies were led by King Louis VII of France and Emperor Conrad III of Germany.

In fact, Eleanor of Aquitaine, the queen of France, accompanied her husband Louis VII on the Second Crusade, which made her one of the most prominent women to participate in the crusading movement.

The Crusaders travelled to Constantinople and marched through Anatolia, which was a predominantly Muslim territory.

Along the way, they were joined by additional soldiers from Italy, as well as others from France who had sailed, rather than walked, to the Holy Land.

The expedition was a catastrophe. The Byzantine emperor had warned the Europeans that the Turkish forces were much stronger than during the First Crusade, and that they needed to exercise caution.

However, the Christian rulers did not heed this advice.

Once in Asia Minor, the two crusader forces, the Germans and the French, split up and took different routes towards the east.

The German army, led by Conrad III, did not take enough supplies and starvation quickly set in.

At Dorylaeum, they were attacked by the Seljuk Turks on the 25th of October 1147 and were driven back to the city of Nicaea.

Conrad was wounded and fled back to Constantinople.

The French army, under Louis VII, defeated a Seljuk force in December 1147 but then suffered a severe defeat on the 7th of January, 1148, while crossing the Cadmus Mountains. 

By the time they reached the Christian city of Antioch in March 1148, the army was in a shambles.

Ultimately, the Turkish forces had decimated 90 percent of the German army and half of the French troops while they had been attempting to cross Anatolia. 

Around this time, Conrad had rejoined Louis with his remaining troops.

On the 24th of July 1148, the combined crusader army tried an ill-advised and ill-planned attack on the Muslim city of Damascus, one of the wealthiest capitals in the region. 

However, after just four days of ineffective siege warfare, the crusaders' assault on Damascus was called off.

This was mainly due to insufficient water supplies for their soldiers.

Then, the Europeans received word of a large Muslim army forming nearby, which caused panic among the Crusaders.

As a result, it was decided to call an end to the rest of the crusade. Conrad III returned to his lands in Europe in September of 1148 and Louis did the same six months later.

The Second Crusade had been a clear military failure.

After the failed Second Crusade, two great Muslim leaders emerged: Nur ad-Din and Saladin. Nur ad-Din was the ruler of Syria and Egypt.

He was a pragmatic man who worked to unify the Muslims. Saladin was one of his generals.

He was from a Kurdish family who had migrated to Turkey. 

In 1154, Nur ad-Din seized Damascus and devised a comprehensive plan to surround the Crusader states by conquering Egypt to the south.

The Fatimid rulers of Egypt were assisted against crusader assaults by Nur ed-Din's troops.

Saladin was one of Nur ad-Din's Egyptian expedition commanders and, in 1169, Nur ad-Din made him overall commander of his forces there.

In 1171 Saladin overthrew the Fatimid caliph. Although he was officially working for Nur ad-Din, the thirty-three-year-old Saladin essentially became the ruler of Egypt.

When Nur ad-Din died in 1174, Saladin became the ruler of both Egypt and Syria, founding the Ayubid dynasty.

In 1185, an 8-year-old boy, called Baldwin V, became the king of Jerusalem. In 1186, a Frankish nobleman broke the terms of a truce with Saladin and pillaged an enormous trade caravan making its way from Egypt to Damascus.

Saladin's sister was travelling with the caravan and, as a result, Saladin was outraged.

In response, Saladin invaded the kingdom of Jerusalem with a force of 20,000 men in May 1187 and captured the city of Tiberias from the Crusaders.

This was a strategic victory because it cut off the Christians' access to the Sea of Galilee, which was their main source of supplies.

In July Saladin faced off against a crusader army about the same size as his own, near two hills: the Horns of Hattin, west of the Galilee Sea.

The Franks, who accounted for the majority of the crusader army, marched north to try to recapture Tiberias, but made the error of camping on a plateau where there was no access to fresh water.

By dawn on the battle's third day, when it was already scorching outside, the army was parched with thirst.

Weak and isolated, the crusader army was systematically destroyed by Saladin's army. Almost all of the Frankish leaders were killed or captured.

With the loss of so many men and valuable leaders, the city of Jerusalem was vulnerable to attack.

He then spent the next two months pressuring Crusader strongholds in Galilee and on the Mediterranean coast.

Eventually, the two settlements of Acre and Gaza were captured by his troops. The crucial coastal city of Tyre was able to hold out, however.

Finally, Saladin turned his forces towards Jerusalem and besieged it beginning on the 20th of September 1187.

Jerusalem eventually surrendered to him on the 2nd of October 1187.

Rather than massacring the Christian soldiers and citizens in Jerusalem, Saladin gave them amnesty.

He accepted payment from some of the rich nobles to allow them to leave the city, while others continued to live under his rule.

With the fall of Jerusalem to the Muslim forces, the last remaining major Crusader stronghold in the Holy Land was the coastal city of Tyre.

The Third Crusade was called by Pope Gregory VIII in 1187, after the Muslims had recaptured Jerusalem from the Christians.

The main armies were led by Philip II of France and Frederick I, the Holy Roman Emperor.

They were joined by a large army from England, led by King Richard I (also known as "Richard the Lionheart"). 

Frederick marched out in May 1189, with an army of around 20,000 mounted knights and foot soldiers.

However, when they were attempting to cross the Saleph River in eastern Anatolia in June 1190, the emperor drowned.

His troops then dispersed.

The other Crusaders marched to the city of Acre, arriving in the early summer of 1191.

On July 12 they accepted the city's surrender, agreeing to spare their lives in return for a payment of large sum of money and the release of 1500 Christian prisoners.

However, by August, Saladin failed to pay the agreed sum, and, in response, Richard killed 2700 captured Muslim soldiers who had garrisoned the city.

In the same month, Philip II of France ended his participation in the crusade due to leadership disagreements with Richard I of England and headed back home to France.

This left Richard as the most important commander of the remaining European forces.

For the next year, Richard and Saladin attempted to outwit each other, both militarily and diplomatically.

Richard won most of the military confrontations, demonstrating outstanding personal bravery on several occasions.

However, his forces were insufficient to hold much of Palestine or, to capture Jerusalem. 

Finally, in 1192, a truce was signed between Richard and Saladin, which was called the Treaty of Ramia.

The Franks were permitted to keep a strip of coastline from Acre down to Jaffa, and Christian pilgrims were once again able to visit all of Palestine's holy sites.

With the crusade officially over, Richard then departed for home.

The Fourth Crusade was called for by Pope Innocent III in 1202, to take back the city of Jerusalem from the Muslims once more.

Count Baldwin IX of Flanders and Marquis Boniface of Montferrat led the main army, and they decided to attack Egypt first, rather than marching through Asian Minor as the previous crusaders had done.

Travel from Europe to the Holy Land once more became a challenge for the crusading armies.

However, wealthy traders from Venice offered to transport the entire army to Egypt for a price.

The Crusaders accepted their offer and, in 1202, set sail for Venice.

After arriving in Venice, the Crusaders found that they did not have enough money to pay for their passage.

The Venetians were unwilling to move the Crusade's fleet without being compensated, so an agreement was reached: in exchange for transportation, the Crusaders would help the Venetians conquer Zara (a Christian city). 

The Pope forbade such an action against other Christians but, after much discussion and debate, the majority of the Crusade's leaders decided to follow through with the deal.

In November 1202, they conquered Zara and then continued on to Constantinople.

Once in Constantinople, the Crusaders found themselves at odds with the city's emperor, Alexius III.

The emperor refused to honor his agreement with Marquis Boniface and provide troops for the Crusade.

In response, the Crusaders captured and then sacked the city of Constantinople in 1204. 

After a period of time, order was restored and a new emperor, Baldwin I, was crowned.

A new Latin Empire was established with its capital in Constantinople. With Jerusalem still under Muslim control, however, the Crusade ultimately failed in its main objective and was called off.

By the end of the Fourth Crusade, the Christian world was in disarray. The Pope and the Eastern Orthodox Church were at odds, while the Latin Empire held Constantinople.

Although Jerusalem remained under Muslim control, the Europeans had established a number of Crusader states along the Mediterranean coast.

The Crusades also had a significant impact on European society. They increased contact between Europeans and Muslims, exposing both sides to new ideas and technologies.

The Crusades also helped to solidify a sense of national identity for both France and England.

For centuries after the last Crusade, Europe would be changed by its experience with holy war.