King David could not allow Ilghazi to unite with the Tbilisi Muslims, so he decided to intercept him on his way there. He used a strategy of surprise and to entice the enemy step-by-step into a trap. He chose a mountainous and wooded area near the Didgori Mountain range, situated between Manglisi and Tbilisi, to attack. "On August 11, 1121, King David led his army along the Nichbisi valley from the ancient capital of Mtskheta and divided his troops into two parts, one under his personal command and the other smaller group under his son Demetrius I, hidden in reserve behind the nearby heights with orders to attack the flank at a given signal." (Mikaberidze, "Miraculous Victory")