When the troops retired a good many of the slain, together with their arms and ammunition, fell into the hands of the rebels. The column withdrew to Nha-Nam, and reinforcements of men, guns and mortars were sent from Bac-Ninh. Colonel Frey, who commanded the brigade, arrived, and took over the direction of the operations, which lasted from the 30th December to the 11th January, 1891. Trenches were opened, but progress was very slow. Eventually, a position was reached about 100 yards from the first palisade, from which a glimpse of the interior of the fort could be obtained. A battery composed of two mountain guns and as many small mortars was established, and the shells thrown from them soon caused serious loss to the enemy, and set fire to one of the thatched roofs of the numerous buildings it contained. Most of these constructions were built of bamboo and plaster, so that the conflagration spread rapidly; and towards evening the interior of the citadel was a mass of flames. The rebels displayed striking courage, for they clung to the walls, and fired incessant volleys at the guns until late into the night. Profiting by the darkness, they then evacuated the fort, after burying their dead, and retired with their wounded to positions a few miles further north. [Illustration: INTERIOR OF THE FORT AT HOU-THUÉ.] These positions were stronger than at Hou-Thué, and consisted of a big entrenched village, the approaches being covered by several forts and numerous rifle-pits, the importance of which was unknown to the French, so well had the secret of their construction been guarded. On the following morning an assaulting column found the position at Hou-Thué empty, and the defences were partially destroyed by dynamite.[1] After a few reconnoitring parties had been sent out, and no trace of the enemy discovered, the civil authorities concluded that the rebellion had been squashed, and the Governor gave orders for the column to be broken up. [Footnote 1: A most excellent and detailed account of the operations against Hou-Thué is to be found in "Pirates et Rebelles au Tonkin," by General Frey, published in 1892 by Messrs Hachette et Cie, Paris. The maps of the region and sketches of the position are reproduced from that work by the kind permission of the author and publishers.] However, to ensure tranquillity, it was decided to maintain the garrison, and strengthen the position at Nha-Nam, situate about 3 miles south-west of Hou-Thué, on a small elevation dominating to the south, east, and west the plain which extends towards the Song-Cau and Song-Thuong rivers, and northwards of which is the mass of forest-covered hills already described.