On 28 June 1119, Roger of Salerno – the southern Italian Norman ruler of the Latin principality of Antioch – was defeated in the Battle of the Field of Blood (Ager Sanguinis), in northern Syria, by a Muslim army from Aleppo led by the Turcoman warlord Najm al-Din Il-Ghazi b. Artuq of Mardin. The Field of Blood was a catastrophe for the Franks who had settled in Syria in the wake of the First Crusade. Roger of Salerno himself was slain, the Antiochene relic of the True Cross was lost and the bulk of the Latin principality's army – estimated at 700 knights and 3,000 infantrymen – were either killed or taken into captivity.

One of the most important contemporary accounts of these events was preserved in Walter the Chancellor's Bella Antiochena (The Antiochene Wars). Walter appears to have been a highly placed Antiochene official who served as the Latin principality's chancellor between c.1114 and c.1122. He authored a Latin narrative of the Battle of the Field of Blood and its aftermath, as well as describing an earlier campaign fought in 1115, and his chronicle has long been regarded as a valuable source for the early history of the northern Crusader states – offering a detailed record of events that certainly could be characterised as well informed and that often seems to draw from Walter's own eyewitness experiences and memories.

The Nature of Walter the Chancellor's Bella Antiochena

Bella Antiochena appears to have been composed in at least two distinct phases. Book One, covering the events of 1115 and Roger of Salerno's victory at the first battle of Tell Danith against Bursuq of Hamadan on 14 September 1115, was probably completed before 1119. Book Two recounted the Frankish disaster at the Field of Blood, the subsequent arrival of King Baldwin II of Jerusalem in northern Syria and the partial recovery of Frankish fortunes heralded by Baldwin's victory in the second battle of Tell Danith on 14 August 1119. Walter the Chancellor was almost certainly present at the Field of Blood and appears to have been among those taken prisoner after the battle.