This was the hardest march it has ever been my lot to undertake, and, as already stated, we covered close upon 32 miles in about eight hours. The garrison--they were _tirailleurs_, for the detachment of the Legion had left more than a month before--was on the alert when we arrived, but had seen no sign of brigands. We were all glad to get inside the fort and take a few hours' rest. During the morning a telegram was received, stating that the band had taken another direction, and that all danger was passed. Desiring, no doubt, that we should not pass the night in so unhealthy a region, Captain Perrin, who had come with us, started us on our way back at two in the afternoon. We went at a moderate speed, passing the night at Cho-Thuong, where there are some wonderful caves, the entrance to which is some 60 feet from the ground. In these some of us tried to sleep, but were driven away by a host of parasites. Access was gained to these caverns by means of long bamboo ladders. When their village, which is situated at the base of the rock, is attacked by bandits, the Muongs take refuge with their women and children in these caves, where, after hoisting up the ladders, they are absolutely secure from attack. Strange to say, they succeed in getting their cattle into these shelters in time of danger, but whether they do so by the aid of ropes, or through some lower entrance known only to themselves, I was unable to ascertain. We reached Bo-Ha at three in the afternoon on the following day. During the next few weeks our detachment was kept very busy preparing things for the troops, which were soon to be concentrated at this point; and we spent a considerable part of our time working at the road from the landing-stage on the Song-Thuong up to the fort. This had to be widened and levelled so as to allow of the passage of field artillery. It was very evident that the rebels were alive to the fact that operations against them were intended, for their vedettes were continually in evidence round Bo-Ha and Nha-Nam, and along the road between these forts. No movement could be made by the troops of these two garrisons without it being at once signalled by the enemy's scouts. Their methods for communicating information at a distance were really ingenious. By day they made use of a code of smoke signals, to obtain which torches composed of chopped straw, resin and gunpowder were used; at night oil lanterns with a sliding shutter attachment, or paper balloons carrying a burning rag soaked in petroleum, served the same purpose. Stores and ammunition continued to arrive, so that temporary sheds had to be erected outside the fort, for the go-downs inside were filled to overflowing.