The Historia Ierosolimitana, or ‘The History of the Jerusalemites’, is a Latin prose history of the First Crusade of around 40,000 words, written by Baldric, the abbot of the Benedictine abbey at Bourgueil, in the middle of the first decade of the twelfth century. It is translated here into a modern language for the first time. This introduction will try to meet the needs of those studying the historical sources of the First Crusade through a discussion of several questions, including: Who was Baldric and why did he write this book? Where did Baldric get his information from and how reliable is it as an account of the First Crusade? How much did Baldric simply report the information he received and how much did he modify it to convey his own particular message? If others writing about the First Crusade used the same information source as Baldric, in what ways did his use of that source differ from his contemporaries? What debates are there about the sources used by Baldric and others writing about the First Crusade? Did Baldric have a particular writing style and what use did he make of literary devices, including quotations from the Bible and classical texts? What influence did the Historia have on medieval authors?

The text of the History is presented as a prologue followed by four books, a format found in all the surviving medieval manuscript versions. Baldric drew most of its evidence and narrative structure from the Gesta Francorum, which functioned as his primary source document. The History begins with Pope Urban II's sermon at the Council of Clermont in November 1095, to which Baldric was almost certainly an eyewitness; it narrates the passage of the Jerusalemites to the Holy Land; says a great deal about the siege and occupation of Antioch; outlines the journey south and the capture of Jerusalem, and ends with the defeat of an Egyptian army at Ascalon in August 1099.

A medieval text, such as this history of the First Crusade, is of value to historians in three main ways: as a record and means for transmitting historical facts; as a way of understanding the perspective of the person who wrote it and the world in which it was written; and as part of a manuscript tradition revealing how the text was copied or used during the Middle Ages.