During the twenty days of his halt at Alagon, Moncey had employed his sappers and many of his infantry in the manufacture of gabions, wool-packs, and sandbags for the projected siege. He was continually receiving convoys of heavy artillery and ammunition from Pampeluna, and when Mortier came up on December 20, had a sufficiency of material collected for the commencement of the leaguer. The two marshals moved on together on that day, and marched eastward towards Saragossa, with the whole of their forces, save that four battalions were left to guard the camp and dépôts at Alagon, and three more at Tudela to keep open the Pampeluna road[117]. Gazan’s division crossed the Ebro opposite Tauste, to invest the transpontine suburb of Saragossa: the rest of the army kept to the right bank. Late in the evening both columns came in sight of the city. They mustered, after deducting the troops left behind, about 38,000 infantry, 3,500 cavalry, and 3,000 sappers and artillerymen. They had sixty siege-guns, over and above the eighty-four field-pieces belonging to the corps-artillery of Mortier and Moncey. The provision of artillery was copious--far more than the French had turned against many of the first-class fortresses of Germany. The Emperor was determined that Saragossa should be well battered, and had told off an extra proportion of engineers against the place, entrusting the general charge of the work to his aide-de-camp, General Lacoste, one of the most distinguished officers of the scientific corps. [116] See the table in Belmas, ii. 381. [117] These were all detached from Moncey. The Alagon garrison consisted of four battalions of the 2nd Legion of Reserve, 2,500 strong. At Tudela were three battalions of the 121st regiment, 1,800 bayonets. When the reinvestment began, Gazan on the left bank established himself at Villanueva facing the suburb of San Lazaro. Mortier with Suchet’s division took post at San Lamberto opposite the western front of the city. Moncey, marching round the place, ranged Grandjean’s troops opposite the Monte Torrero, on the southern front of the defences, and Morlot further east near the mouth of the Huerba. His other division, that of Musnier, formed the central reserve, and guarded the artillery and the magazines. The Spaniards made no attempt to delay the completion of the investment, and kept quiet within their walls.