But all this time the enemy had been busy. At the beginning of the battle the Khalifa had posted a small force of 700 men on his extreme right, to prevent his line of retreat to Omdurman being harassed. This detachment was composed entirely of the Hadendoa tribesmen of Osman Digna's flag, and was commanded by one of his subordinate Emirs, who selected a suitable position in the shallow khor. As soon as the 21st Lancers left the zeriba the Dervish scouts on the top of Surgham carried the news to the Khalifa. It was said that the English cavalry were coming to cut him off from Omdurman. Abdullah thereupon determined to strengthen his extreme right; and he immediately ordered four regiments, each 500 strong, drawn from the force around the Black Flag and under the Emir Ibrahim Khalil, to reinforce the Hadendoa in the khor. While we were waiting for orders on the ridge these men were hurrying southwards along the depression, and concealed by a spur of Surgham Hill. The Lancer patrol reconnoitred the khor, at the imminent risk of their lives, while it was only occupied by the original 700 Hadendoa. Galloping back, they reported that it was held by about 1,000 men. Before they reached the regiment this number was increased to 2,700. This, however, we had no means of knowing. The Khalifa, having despatched his reinforcement, rode on his donkey with a scanty escort nearly half a mile from the Black Flag towards the khor, in order to watch the event, and in consequence he was within 500 yards of the scene.