Thread by @MedievalScholar

In 1095, the Pope himself made the call for a crusade. Promising warriors who embarked to be absolved of their sins.

Countless thousands of people made the journey to Constantinople, seeking to take back the holy land, and Jerusalem itself.

In the First Crusade 🧵

By the 11th century, Europe’s population was growing significantly due to agricultural and technological advances that promoted trade.

Feudalism and manorialism structured society, where nobles provided military service in exchange for land rights.

The Catholic Church wielded immense influence, particularly as the Gregorian Reform movement in the 1050s sought to consolidate power.

This reform led to conflict with the Eastern Orthodox Church, which opposed papal supremacy. Disputes over doctrine culminated in the East-West Schism of 1054, when Pope Leo IX and Patriarch Michael I Cerularius excommunicated each other.

The Christian tradition of holy war, originating from the teachings of Augustine of Hippo, gained traction as a way to justify conflict under certain conditions.

With the collapse of the Carolingian Empire, a warrior class emerged, often engaging in violent feuds. The Church attempted to channel this violence for communal defense or reclaiming land, notably in Christian campaigns against Muslims in Iberia and Sicily.

Pope Alexander II and later Gregory VII introduced systems to recruit knights through oaths, helping supply military support for religious conflicts across Europe.

The Christian kingdoms on the Iberian Peninsula, fragmented yet militarily capable, took advantage of the weakened Caliphate of Córdoba to reclaim territories in the 11th century, marking the beginning of the Reconquista.

Meanwhile, the Islamic world also saw major changes with the arrival of the Turkic Seljuks, a minor clan that converted to Islam and expanded their power in the 10th century.

The Seljuks, who were culturally distinct from their Arabic-speaking subjects, conquered Iran, Iraq, and the Near East, sparking conflicts with the Shi'ite Fatimid Caliphate in Syria and Palestine. Their nomadic traditions and decentralized rule weakened local governance, leading to internal rivalries.

In 1071, the Eastern Roman Emperor Romanos IV Diogenes faced a severe defeat at the hands of the Seljuks at the Battle of Manzikert, marking a major setback and loss of key cities such as Nicaea and Antioch.

These losses increased Western interest in reclaiming historically significant cities, contributing to the motivations behind the First Crusade.

Eastern Roman Emperor Alexios I Komnenos wrote in a letter to Robert II of Flanders:

The holy places are desecrated and destroyed in countless ways. Noble matrons and their daughters, robbed of everything, are violated one after another, like animals. Some [of their attackers] shamelessly place virgins in front of their own mothers and force them to sing wicked and obscene songs until they have finished having their ways with them... men of every age and description, boys, youths, old men, nobles, peasants and what is worse still and yet more distressing, clerics and monks and woe of unprecedented woes, even bishops are defiled with the sin of sodomy and it is now trumpeted abroad that one bishop has succumbed to this abominable sin.

Once more the Eastern Romans would come under siege by local warlords, and Emperor Alexios Komnenos wrote to Pope Urban II, calling for aid from Christian Europe.

Pope Urban II saw this situation as a prime opportunity to mend many issues ailing the Christian world, he would seek to rebuild bridges between the Catholic and Orthodox churches since the Great Schism of 1054.

Pope Urban II would call for a Crusade at the Council of Clermont in 1095 where he implored knights and warriors to take up arms and embark on a sacred mission to reclaim Jerusalem from Muslim control, promising salvation to those who joined the cause.

The First Crusade began chaotically when untrained armies of peasants and minor nobles, inspired by the preacher Peter the Hermit, set off for Jerusalem months before the official crusade’s start.

Despite a lack of discipline, Peter's followers, among whom were some knights, like Walter Sans Avoir, marched through Christian lands, causing conflicts and pillaging, especially in Belgrade and Hungary.

When they reached Constantinople, the Byzantine Emperor Alexios I quickly ferried them across the Bosporus to avoid trouble. However, once in Seljuk territory, they were quickly decimated, with most of Peter and Walter's followers killed in battles like the Battle of Civetot, where Walter perished.

The crusade's call also triggered horrific violence against Jewish communities in the Rhineland. Months before the main crusade left, rogue crusaders led by Emicho of Flonheim attacked Jewish settlements in Speyer, Worms, and Mainz, resulting in massacres and forced conversions.

Church officials, including the Archbishop of Cologne, attempted to protect the Jewish communities, others extracted payments in return for safety.

Estimates of the First Crusade's size suggest that around 70,000 to 80,000 people left Western Europe shortly after the Council of Clermont, with additional recruits joining later, totaling between 60,000 and 100,000, including 7,000 to 10,000 knights and 35,000 to 50,000 foot soldiers.

Major figures who joined included Bohemond of Taranto, Godfrey of Bouillon, and Raymond IV of Toulouse.

These leaders formed four main armies with distinct regional loyalties, united by a shared commitment to reclaim Jerusalem despite sometimes clashing interests.

The crusader armies made their way to Constantinople along different routes. Godfrey traveled overland through the Balkans, while Raymond of Toulouse led his Provençal forces along the coast of Illyria before turning east.

Before they crossed the Bosporus, Alexios advised the crusaders on strategies for confronting the Seljuk forces ahead.

The crusader armies crossed into Asia Minor in early 1097.

Emperor Alexios I sent two of his generals, Manuel Boutoumites and Tatikios, to support the crusaders.

Their first target was Nicaea, formerly an Eastern Roman city but now the capital of the Seljuk Sultanate of Rûm under Kilij Arslan. Arslan, occupied with a campaign against the Danishmends, had underestimated the crusaders and left his family and treasury in Nicaea.

The crusaders arrived on May 14, 1097, and laid siege to the city. Arslan returned to defend Nicaea on May 16 but suffered heavy losses and was forced to retreat.

Although the siege continued, the crusaders struggled to cut off supplies entering the city via Lake İznik. To overcome this, Alexios had ships transported over land to block the lake. Seeing this, the Turkish garrison surrendered on June 18.

The Siege of Antioch would begin on October 20th, 1097 and not end until June 28th, 1098. The crusader force numbering around 40,000 would suffer heavy losses from disease, famine and battle however would claim victory after intense fighting following the breach of the walls.

One of the key stories associated with the siege is the discovery of the Holy Lance, a relic believed to be the lance that pierced Jesus Christ during the Crucifixion. This discovery boosted the Crusaders' morale greatly.

On June 7th, 1099, the Crusaders would arrive at the walls of Jerusalem. The holy objective of their cause.

The Crusaders quickly set up a blockade around the city to begin the siege, with an army of approximately 12,200 to 13,300 men, it would start now.

Godfrey of Bouillon, Robert of Flanders and Tancred planned to siege the city from the north, while Raymond of Toulouse positioned himself and his forces to siege the south.

Due to the wells being poisoned and trees being cut down nearby, the crusaders had either no or extremely limited resources in this regard. However on June 17th, English and Genoese ships arrived in Jaffa carrying key supplies.

Over the course of 2 weeks, the army would construct siege towers, a battering ram, and countless scaling ladders. On the 14th of July their next assault began.

Godfrey and his men were to break through the outer northern walls of the city, they would penetrate the first line of defense that day.

On the South Raymond of Toulouse's forces were met with ferocious resistance by the Fatimids.

On the 15th of July, Godfrey and his allies gained success and the Crusader Ludolf of Tournai would be the first to mount the wall.

The Franks quickly gained control on the wall, and as the city's defenses collapsed, waves of panic shook the Fatimids.

On 15 July 1099, the crusaders made their way into the city through the tower of David and began massacring large numbers of the inhabitants, Muslims and Jews alike.

According to eyewitness accounts the streets of Jerusalem were filled with blood, according to some even up to their ankles.

On July 22nd, Godfrey of Bouillon was made Advocatus Sancti Sepulchri, Defender of the Holy Sepulchre. Refusing to wear a crown of gold on the site where Christ had worn a crown of thorns.

He would become the first ruler of the Kingdom of Jerusalem.

The First Crusade would end after the Battle of Ascalon in August 1099. Godfrey would lead his soldiers, 10,000 men strong with the True Cross and defeat the Fatimid force of 20,000.

The Crusaders launched a surprise attack at dawn, and won the battle in the less than an hour.