The Crusades: the thrill of a priceless manuscript
I first fell in love with crusading history as a schoolboy and continue to be fascinated by these medieval holy wars. In many ways, they have become my life's work.
For me, the Crusades, the wars fought between Christians and Muslims for possession of the Holy Land between 1095 and 1291, have it all - the power to thrill and shock through tales of epic adventure, appalling brutality and intense human drama; and the capacity to ignite and sustain curiosity in the way they impact upon 'big history' themes like the clash of civilisations and the causes of religious violence.
After the publication of my recent general history of the Crusades, I was approached by an independent production company with a view to developing a television series based on my work.
The Crusades, a three-part series was then commissioned by BBC Two, and I embarked upon an intense filming schedule that took me through Turkey, Israel, Jordan, Egypt, France, Italy and the UK over three months, writing and presenting the programme, and working with a brilliant production team.
It's been an extraordinary experience - from the grand spectacle of sailing down the Nile to the intimacy of handling tiny copper coins minted by crusaders - and an immense privilege.
One of the undoubted highlights was gaining access to the Aqsa Mosque archive in the heart of Jerusalem's Old City, to view a priceless, 800-year-old manuscript written by one of the closest advisors to the mighty Muslim Sultan Saladin, the man who re-conquered Jerusalem for Islam.
As far as I know, we were the first Western film crew allowed inside this library just yards from one of Islam's most revered holy sites, and it took months of delicate negotiation to secure permission. The manuscript didn't disappoint.
Its text lays bare Saladin's agony in July 1192, during the Third Crusade, when he decided to abandon Jerusalem to the Christians.
After years of campaigning, both he and his troops were shattered by exhaustion and Muslim morale was faltering.
Under these conditions, and with the crusaders camped just 12 miles away, Saladin judged that he had no hope of holding the Holy City once an attack began. That day he was said to have shed tears of grief as he led his people in prayer.
Richard the Lionheart and Saladin
The manuscript also shows Richard the Lionheart - leader of the Third Crusade - to have been no brutish hothead, but a canny and agile negotiator.
This union would form the basis of a peace agreement in which 'the sultan should give to al-Adil all the coastal lands that he held and make him king of Palestine', with Jerusalem to serve 'as the seat of the royal couple's realm'.
With a flourish of seeming magnanimity, the Lionheart proclaimed that the acceptance of this deal would bring the crusade to an immediate end and prompt his return to the West.
Richard probably had little or no intention of ever following through with this deal. Instead, his aim seems to have been to sow seeds of doubt and distrust within the Muslim camp by playing upon Saladin's fear that his brother al-Adil might seek to usurp power for himself.
I was primed for these revelations, having spent years poring over printed versions of this account.
What I didn't realise was that this manuscript had had something of a secret life. Up until the early 20th Century, the Aqsa archive actually had served as a public lending library.
Amazing as it now sounds, from the later Middle Ages onwards, citizens of Jerusalem had been taking this Life Of Saladin home to read; and over the years some had even left their mark on its pages, inscribing comments ranging from 'Praise be to Allah' to 'It's raining today'.
For me, the experience of actually holding a manuscript written by a man who knew the great Sultan Saladin, who witnessed the Third Crusade first-hand, was simply electrifying.
I couldn't help wondering what all those other readers across the centuries had felt and thought as they held this same work.
Dr Thomas Asbridge is the presenter of The Crusades.
Comments made by writers on the BBC TV blog are their own opinions and not necessarily those of the BBC.