Conflict between Georgian and a Muslim coalition on the Didgori Field near Tbilisi in August 1121; the battle is usually considered the greatest Georgian military success. The late 11th century saw the beginning of the so-called Great Turkish Troubles (didi turkoba) in Georgia when the Seljuk tribes arrived in large numbers to settle on Georgian lands and turned the occupied territory into pastures, undermining local agriculture and the economy. Seljuk dominance continued unchecked for almost a decade and devastated the country. In 1089, a bloodless coup d’etat forced King Giorgi II to abdicate in favor of his 16-year-old son David, who quickly rallied his forces to defeat the powerful enemy and rebuild his country. From 1089–1105, King David attacked isolated Seljuk troops and revived the devastated regions; in 1092, he ceased paying the annual tribute to the Seljuks and ended the seasonal migration of the Turks into Georgia. He then continued his expansion throughout southern Transcaucasia, successfully defeating the Seljuk invasions in 1105, 1110, and 1116. King David reorganized the Georgian army, resettling some 40,000 families of Cuman-Qipcaqs from the northern Caucasus, who provided him with a steady supply of manpower. The new army was immediately put to use as King David began to raid the nearby principalities of Shirwan and Great Armenia. He soon asserted his authority over almost the entire southern Transcaucasia, except for Tbilisi, and some regions of the North Caucasus. He also established contact with the Crusaders in the Holy Land, and there is evidence that the two factions tried to coordinate their actions against the Muslims.
The Muslim powers became increasingly concerned about the rapid rise of the Christian state in the southern Caucasus and even considered it a greater threat than the Crusaders in Palestine, whom they managed to contain on the coast. In 1121, Sultan Mahmud b. Muhammad (1118–1131) declared a holy war on Georgia and rallied a large coalition of Muslim states led by the Artuqid Najm al-din El-ğazi and Toğrul b. Muhammad, the Seljuqid ruler of Arran and Nakhichevan; the coalition was also supported by lesser but important local rulers, including the “king of the Arabs” Dubays b. Sadaqa (1108–1135), and Tughan-Arslan, lord of Arzin, Bidlis and Dvin. Najm al-din El-ğazi had just celebrated his great victory over the Crusaders under King Roger of Antioch at Balat in 1119 and enjoyed the reputation of an experienced Muslim commander. The size of the Muslim army is still a matter of debate with numbers ranging from a fantastic 600,000 men (Walter the Chancellor’s Bella Antiochena, Matthew of Edessa) to 400,000 (Smbat Sparapet’s Chronicle) while estimates of Georgian historians vary between 100,000–250,000. All of these numbers are exaggerated and the size of the Muslim army was hardly in six-figure numbers; still all available sources indicate that Muslims made massive preparations, gathered an army that was several times larger than any engaged in the Holy Land, and vastly outnumbered the Georgians. In mid-summer 1121, the Muslim troops advanced along various routes, with part of them passing the provinces of Arsan al Rum (Erserum) and al-Ghars (Kars) while Sultan Toğrul moved through Ganja and Tughan-Arslan the Hunchback marched from Dvin. Entering Georgian territory, they proceeded by the Manglisi-Didgori valley toward Tbilisi. On 10 August, the enormous Muslim army bivouacked on a vast field near Didgori, about a day’s march from Tbilisi.
The Georgians were well aware of the Muslim preparations and took necessary precautions. King David evacuated the regions along the Muslim invasion route and called up his troops. The Georgians mastered some 56,000 men, including 500 Alans and 200 Crusaders, who had arrived from the Holy Land. On 11 August 1121, he led his army along the Nichbisi Valley from the ancient capital of Mtskheta and divided the troops into two parts with a larger group under his personal command; a smaller detachment under his son Demetre was to occupy secretly the nearby heights and strike the enemy flank at a signal. On the royal orders, the Nichbisi Valley, behind the Georgian troops, was blockaded with fallen trees leaving no other choice for the Georgian troops but to fight to the death. According to the French knight and historian Galterii, King David appealed to his warriors just before the battle, “Soldiers of Christ! If we fight with abandon, defending the faith of our Lord, we shall not only overcome the countless servants of Satan, but the Devil himself. I will only advise you one thing that will add to our honor and our profit: raising our hands to Heaven we will all swear to our Lord that in the name of love to Him, we will rather die on the battlefield than run.”
The Georgian battle plan involved a cunning move. On the morning of 12 August, some 200 cavalrymen departed the Georgian camp and rode to the enemy side, indicating they wanted to defect. The Muslim commanders, surprisingly, not only allowed them into the camp but also gathered to meet them. At a signal, the Georgians suddenly unsheathed their swords and attacked them, killing and wounding most of them. Observing the confusion in the enemy camp, King David ordered a general attack on the enemy positions while his son Prince Demetre charged the enemy flank. With their leadership in disarray, the Muslims in the frontline failed to organize any resistance, while those in the back soon became so disorganized that the entire battle lasted only three hours before the enemy army fled in disorder. According to the Georgian chronicler, King David’s troops pursued them for three days, “putting all of them to the sword and leaving them to the carnivorous beasts and birds of the mountains and plains.” The Armenian historian Matthews wrote that “terrible and savage slaughter of the enemy troops ensued and the [enemy] corpses filled up the rivers and covered all valleys and cliffs,” and claimed that less than a hundred men survived from every thousand. The Muslim commander-in-chief El-ğazi himself was wounded and fled with the few surviving escorts while his son-in-law Dubays b. Sadaqa barely escaped after having his necklace torn off his neck (it was later donated to the Gelati Monastery). The Georgians captured the entire enemy camp and the fabulous riches it contained.
Following his success, King David seized Tbilisi, the last Muslim enclave remaining from the Arab occupation, in 1122 and moved the Georgian capital there. In 1123–1124, Georgian armies were victorious in the neighboring territories of Armenia, Shirwan, and northern Caucasus, greatly expanding Georgia’s sphere of influence. A contemporary chronicler marveled, “What tongue can relate the wonders which our sustaining Christ gave us on that day? And what are the narrations of Homer and Aristotle to me about the Trojan War and the bravery of Achilles or Josephus’ writings about the valor of the Maccabees or Alexander and Titus at Jerusalem?” The battle entered the Georgian national conscience as “the miraculous victory” (dzlevai sakvirveli) and is without doubt one of the apogees of Georgian history. It signaled the emergence of Georgia as a great military power in the late 11th–12th centuries and shifted the balance in favor of Georgian cultural and political supremacy in south Caucasia and the Near East.