At the start of the Siege of Edessa in November 1144, Basil joined with his Catholic and Armenian counterparts, Bishops Hugh and John, to organize the defence of the city. He persuaded Hugh to seek a truce, but the offer did not reach the besieging Turkish commander, Zengi. During the two days of looting and massacre that followed the breaching of the walls on 24 December, Basil had himself led about on a rope, naked and with his beard shaven. Zengi encountered him when he entered the city after the two days. In Zengi's tent, Basil impressed the commander with his humility, courage and fluency in Arabic. Zengi had him dressed and the two of them discussed the rebuilding of the city. According to Michael the Great, "as long as Zengi ruled in Edessa [...] this venerable bishop was very influential." Basil was responsible for repopulating the city.