This famous fortress, in shape, roughly resembles a triangle with the angles truncated. The base, looking to the south, is covered by the Agueda, a river given to sudden inundations; the fortifications were strong and formidably armed; as outworks it had to the east the great fortified Convent of San Francisco, to the west a similar building called Santa Cruz; whilst almost parallel with the northern face rose two rocky ridges called the Great and Small Teson, the nearest within 600 yards of the city ramparts, and crowned by a formidable redoubt called Francisco. The siege began on January 8. The soil was rocky and covered with snow, the nights were black, the weather bitter. The men lacked entrenching tools. They had to encamp on the side of the Agueda farthest from the city, and ford that river every time the trenches were relieved. The 1st, 3rd, and light divisions formed the attacking force; each division held the trenches in turn for twenty-four hours. Let the reader imagine what degree of hardihood it took to wade in the grey and bitter winter dawn through a half-frozen river, and without fire or warm food, and under a ceaseless rain of shells from the enemy's guns, to toil in the frozen trenches, or to keep watch, while the icicles hung from eyebrow and beard, over the edge of the battery for twenty-four hours in succession. Nothing in this great siege is more wonderful than the fierce speed with which Wellington urged his operations. Massena, who had besieged and captured the city the year before in the height of summer, spent a month in bombarding it before he ventured to assault. Wellington broke ground on January 8, under a tempest of mingled hail and rain; he stormed it on the night of the 19th. He began operations by leaping on the strong work that crowned the Great Teson the very night the siege began. Two companies from each regiment of the light division were detailed by the officer of the day, Colonel Colborne, for the assault. Colborne (afterwards Lord Seaton), a cool and gallant soldier, called his officers together in a group and explained with great minuteness how they were to attack. He then launched his men against the redoubt with a vehemence so swift that, to those who watched the scene under the light of a wintry moon, the column of redcoats, like the thrust of a crimson sword-blade, spanned the ditch, shot up the glacis, and broke through the parapet with a single movement. The accidental explosion of a French shell burst the gate open, and the remainder of the attacking party instantly swept through it. There was fierce musketry fire and a tumult of shouting for a moment or two, but in twenty minutes from Colborne's launching his attack every Frenchman in the redoubt was killed, wounded, or a prisoner.