So completely commanded were all the bridges and fords over the Arlanzan by the castle guns, that two days elapsed ere the allies could cross; but on the 19th, the passage being effected above the town, Major Somers Cocks with the 79th, supported by Pack’s Portuguese, drove in the French outposts on the hill of San Michael, and in the night, reinforced with the 42nd Regiment, assailed the horn-work. The conflict was murderous. The main storming column was beaten off, and the attack would have failed if Cocks had not forced an entrance by the gorge. The garrison was thus cut off, but the assailants not being closely supported the French broke through them. The troops complained of each other, and the loss was above four hundred, while that of the enemy was less than one hundred and fifty. The defences of the castle were feeble and incomplete, yet Wellington’s means were so scant that he relied more upon the enemy’s weakness than his own power. However, it was said water was scarce, and that the provision-magazines might be burned; wherefore twelve thousand men were set to the siege while twenty thousand formed the covering army. For the attack, the trenches were to be opened on the right of San Michael towards the town, and a battery for five guns established on the right of the captured horn-work. A sap was then to be pushed from the trenches towards the first wall, and from thence the engineer was to proceed by gallery and mine. When the first mine should be completed, the battery from San Michael was to open against the second line of defence, and the assault given on the first line. Approaches were then to be continued against the second line, and the battery turned against the third line, in front of the White Church, where the defences were exceedingly weak. Meanwhile a trench for musketry was to be dug along the brow of San Michael, and a concealed battery prepared within the horn-work for a final attack on the Napoleon battery; but the artillery consisted of only three eighteen-pounders with five iron twenty-four-pound howitzers: slender means which, rather than the defects of the fortress, governed the line of attack. When the horn-work fell, a lodgement was commenced in the interior, and continued vigorously under a destructive fire from the Napoleon battery, but good cover was obtained in the night.