Macdonald now, whose army had been reinforced, took a position at Perillo and at Mora, to cover the siege against any interruption on the side of Tarragona, the only quarter from whence an effort in aid of Tortosa could be apprehended; and Suchet, secure from all farther attempts either from Valencia or Aragon, passed twelve battalions across the river at Xerta to the left bank, and in one day completed the investment of the place. The besiegers had great difficulties to overcome, the soil being everywhere rocky, ... so that the engineers were obliged to form parapets and sacks of earth, and in many places to work their way in the trenches by means of gunpowder. The trenches were opened on the night of December 20; and the siege from that hour was carried on with an alacrity and skill in which the French are never wanting. On the twelfth night the enemy had established themselves at the bottom of the ditch; they had then bombarded the city for four days, ... two days they had been engaged in mining, and there were three breaches in the body of the place: but there were nearly 8000 troops within the walls; there was a brave and willing people, and there were the examples of Zaragoza and Gerona. They were in no danger of famine, for the place had been abundantly provided; there was no want of military stores, and the besieging army did not exceed 10,000 men. ♦O’DONELL’S PLAN FOR RELIEVING THE PLACE.♦ Meantime O’Donell had concerted a bold and hopeful enterprise for its relief. He knew that there were provisions and ammunition sufficient for two months’ consumption in the city; he had full reliance upon the disposition of the people, and the whole conduct both of the garrison and the governor from the time that the enemy appeared before the walls had given him reason to confide in both. With his own force he was aware that nothing could be done against the besieging army, covered as it was by Macdonald; but he proposed that Bassecourt should supply 3000 foot and 500 horse from the Valencian army; that the central army should detach 4000 foot and 200 horse; that these should unite under Carvajal with such forces as Aragon could furnish, make demonstration upon the Ebro as if their intention was to succour Tortosa, but there turn off from the most convenient point, and by forced marches proceed to Zaragoza, whither O’Donell would at the same time detach 4000 foot and 400 horse by way of Barbastro. It was believed that the French at this juncture had not more than 4000 men in the whole of Aragon, and the garrison of Zaragoza consisted almost wholly of convalescents and invalids. Bassecourt assented heartily to this well-devised plan; from the central army a refusal was returned, ... perhaps it could not then have mustered even the small force that was required from it; but upon receiving this reply Bassecourt dispatched an officer to the Empecinado, and that intrepid and excellent partisan cheerfully engaged to co-operate.