For mile after mile on those four roads the dust cloud continued. The scout checked off the distances by villages on his map. Adding the length of the four roads together he estimated that about twenty miles of road was occupied by the marching force. It was a whole army corps, then, that was endeavouring to turn their flank. In the open fields between the roads he could distinguish small bodies of cavalry advancing in the same direction. The mass on the roads was certainly infantry, broken here and there by long columns of artillery. The low dense clouds of dust kicked up by the tramp of thousands of feet were cut into short sections where the guns and wagons of the batteries rolled onward. From a rough calculation of those intersected clouds he decided that four brigades of artillery were on the march. He had descended now to 2000 feet, and he kept at that height as he roared over the plodding columns. Behind him his pursuer had lessened the distance between them, was getting dangerously close. The biplane on his right was also approaching. Nevertheless, the scout held on his way comfortably. There was nothing to prevent him carrying out his plan. He was already well beyond the prolongation of his own army's line of battle when he reached the head of the marching infantry. Contrary to his expectation, however, they were not wheeling to the right. They continued straight on, marching away from the battle, it seemed. The scout was puzzled for a moment. He searched the ground in front of him for more troops. It was apparently empty. Then, from a fold in the landscape considerably ahead, he saw another, smaller dust cloud arise. At his highest speed he raced towards it, overtook it in less than a minute. Below him a cavalry brigade, accompanied by two batteries of horse artillery, was trotting sharply forward. What was their objective? He scanned the country in front of them intently. Some three miles ahead of the cavalry was a wooded hill. He picked it out on the map, saw instantly that it commanded the main avenue of retreat of his army. The enemy's plan was clear. He would occupy it with the cavalry and the two batteries until the infantry got up. The threatened army, then attacked in flank and rear, would find its retreat cut off. If the scout's commander was aiming to repeat Salamanca, the enemy was endeavouring to repeat Jackson's march at Chancellorsville. The danger was pressing. The scout reckoned that within half an hour the hostile cavalry would be in possession of that hill. In an hour the infantry would begin to come up in support. Where was the Sixth Division that he had been told would check the flank movement of the enemy? He searched for it, saw a brown mass about two miles from the wooded hill. Its cavalry might get there in a quarter of an hour by a rapid dash. He had then a quarter of an hour to deliver his message and get the division set in motion. The hour was 12.46.