Mbh 6.95.1d

Beholding them repulsed from the encounter by means of the shafts shot from the bow of Drona’s son, Bhimasena’s son Ghatotkacha of gigantic size was filled with rage. He then exhibited a fierce and awful illusion. Therewith that prince of the Rakshasas, endued with extraordinary powers of illusion, confounded the son of Drona in that battle. Then all thy troops, in consequence of that illusion, turned their backs upon the field. They beheld one another cut down and lying prostrate on the surface of the earth, writhing convulsively, perfectly helpless, and bathed in blood. Drona and Duryodhana and Salya and Aswatthaman, and other great bowmen that were regarded as foremost among the Kauravas, also seemed to fly away. All the car-warriors seemed to be crushed, and all the kings seemed to be slain. And horses and horse-riders seemed to be cut down in thousands. Beholding all this, thy troops fled away towards their tents. And although, O king, both myself and Devavrata cried out at the top of our voices, saying, ‘Fight, do not fly away, all this is Rakshasa illusion in battle, applied by Ghatotkacha,’ yet they stopped not, their senses having been confounded. Although both of us said so, still struck with panic, they gave no credit to our words. Beholding them fly away the Pandavas regarded the victory to be theirs. With Ghatotkacha (among them) they uttered many leonine shouts. And all around they filled the air with their shouts mingled with the blare of their conches and the beat of their drums. It was thus that thy whole army, routed by the wicked Ghatotkacha, towards the hour of sunset, fled away in all directions.”