The First Crusade: KS3 History Guide

In November 1095, Pope Urban II rose to address a crowd at Clermont in France and called for an armed pilgrimage to reclaim Jerusalem. What followed over the next four years would reshape the medieval world and leave a legacy historians still wrestle with today — not least because the surviving sources tell only one side of the story.

Why did the First Crusade happen?

Jerusalem had been under Muslim rule since 638 CE. For centuries, Christian pilgrims had generally been able to travel to the city, though conditions varied depending on who governed the region. That changed in the 1070s and 1080s, when the Seljuk Turks expanded rapidly across the Middle East, disrupting pilgrimage routes and threatening the Byzantine Empire — the Christian empire centred on Constantinople (modern Istanbul). Byzantine Emperor Alexios I appealed to the Pope for military assistance, a request that gave Urban II a far larger opportunity than Alexios may have intended.

Historians debate whether religious motivation, political ambition, or social and economic factors drove the First Crusade. Most now argue it was a combination. Before settling on an argument, consider that different participants may have been motivated by very different things.

Pope Urban II's call to arms

Urban II's speech at Clermont in November 1095 is one of the most consequential in medieval history — yet no verbatim transcript survives. What we have are accounts written by chroniclers years after the event, all of them Christian. Historians debate what exactly Urban promised and why the response was so overwhelming. He appears to have offered remission of sins to those who took up the armed pilgrimage, framing the campaign as an act of piety pleasing to God.

But the causes extended beyond religion. Urban sought to assert papal authority over a fractured Christendom. Younger sons without land inheritance saw opportunity for wealth and status. Merchants looked for new trade routes. The evidence pushes in different directions. Before settling on a single cause, ask yourself: which source are you relying on, and who wrote it?

From Clermont to Jerusalem: the march east

The enthusiasm Urban's speech unleashed was immediate — and not always organised. In 1096, a mass of poorly armed peasants and minor clergy, inspired by the preacher Peter the Hermit, set out in what historians call the People's Crusade. Most were massacred by the Seljuk Turks before they reached Jerusalem.

The main Crusading armies — better armed and led by powerful nobles — departed in 1096 and converged on Constantinople. They captured Nicaea in 1097 and endured a gruelling, months-long siege of Antioch in 1097–1098. Bohemond of Taranto secured control of Antioch for himself rather than returning it to Byzantium — an early sign that political ambition ran alongside religious purpose throughout the campaign.

Crusader leaders: who led the armies?

The siege of Jerusalem, 1099

The Crusading army reached Jerusalem in June 1099 and besieged the city for over a month. On 15 July 1099, they broke through the walls. Contemporary Christian chroniclers describe what followed as a brutal massacre of the Muslim and Jewish inhabitants of the city. Their accounts — describing streets flowing with blood and bodies piled in the streets — were sometimes written in triumphant terms, framing the violence as God's judgement. Historians debate the exact scale of the killing, but the consistency of evidence across multiple independent Christian accounts makes widespread violence clear.

Godfrey of Bouillon declined the title of King of Jerusalem, taking instead the title "Advocate of the Holy Sepulchre." The Kingdom of Jerusalem was established as a Crusader state and endured, in various forms, until Saladin recaptured the city in 1187.

The problem of sources: whose story is this?

This is one of the most important questions to ask about the First Crusade, and it lies at the heart of KS3 source work. Every surviving eyewitness account of the campaign was written by a Christian — either a Western Latin chronicler or a Byzantine Greek observer. No Muslim or Jewish eyewitness account from the siege of Jerusalem in 1099 survives from that time.

The Arab historian Ibn al-Athir wrote about the Crusades in the early thirteenth century — over a century after the events he described. What does this mean for the history we can write? It does not mean the Muslim or Jewish experience was unimportant. It means those sources either did not survive or were never recorded in forms that reached us. Before settling on any conclusion about the First Crusade, ask yourself: what would the history look like if we had equivalent contemporary accounts from the other side?

Frequently asked questions

What were the main causes of the First Crusade?

The evidence pushes in different directions. Religious causes were genuine: Urban II framed the campaign as a spiritually meritorious armed pilgrimage, and many participants believed this sincerely. Political causes also mattered: the Pope wanted to assert authority over Christendom, and Alexios I needed military help against the Seljuks. Social and economic factors — landless younger sons, merchants seeking trade routes, the appeal of adventure and status — drove recruitment too. Historians debate which mattered most; most now argue it was a combination of all three working together.

What happened during the siege of Jerusalem in 1099?

The Crusaders breached Jerusalem's walls on 15 July 1099 after besieging the city for over a month. Contemporary Christian chroniclers describe a large-scale massacre of the city's Muslim and Jewish inhabitants. Historians debate the exact scale of the killing, but consistent accounts across multiple independent Christian sources make widespread violence clear. The city became the capital of the Crusader Kingdom of Jerusalem, which survived until Saladin recaptured it in 1187.

Who led the First Crusade and where did the armies come from?

The main armies were led by powerful nobles: Godfrey of Bouillon from Lorraine, Raymond of Toulouse from southern France, Bohemond of Taranto from Norman southern Italy, and Robert of Normandy. They were not a unified royal army but a loose coalition of independent forces, which helps explain why disputes over territory — particularly over Antioch — arose during the campaign and complicated relations with the Byzantine Empire.

Why is it difficult to know what Muslim and Jewish people thought of the First Crusade?

All surviving contemporary accounts of the First Crusade were written by Christians. No Muslim or Jewish eyewitness accounts from the siege of Jerusalem in 1099 have survived to the present day. The first major Arab narrative — by Ibn al-Athir — was written more than a century after the events. This source gap means historians must be honest about whose perspective dominates our knowledge of the Crusades, and students should always ask: who wrote this source, and what perspectives are missing?

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