Pacific. Near its centre stands the city of Callao, on the shore at the foot of the coast range of the Cordillera, three miles from the pass through it, which gives access to the beautiful valley of Rimac, in which stands the city of Lima. The port of Callao is a roadstead shut in by two islands. One of them, named San Lorenzo, is seven miles in length, and shelters the roadstead from all winds except those which blow from the west. Off its southern point lies a smaller island called the Fronton. The open water between the two islands is the main entrance to the inner bay, but between the Fronton and the land there is a much narrower passage, called the Boqueron, in which there are only five fathoms of water and many rocks. To the north of the island of San Lorenzo lies a sandbank, off the mouth of the river Rimac, which is called the Bocanegra.
The old walls of the city of Callao were destroyed by an earthquake in 1746. In their place three great circular castles were erected, crowned with lofty towers. Between them stretched the batteries of the arsenal and of San Joaquin, mounted with 165 heavy guns, which swept the whole of the roadstead. Under their fire the Spanish squadron lay at anchor, consisting of the Esmeralda and Venganza, 44 gun frigates; the corvette Sebastiana, of 36 guns; the brigs Pezuela, Maipo, and Potrillo, each of 18 guns; the schooner Montezuma, of 7 guns; the Aranzazu of 5 guns; and twenty-six gunboats, besides six armed merchant vessels.
The 28th February was the day fixed upon by Cochrane for the attack; the same day Pezuela had arranged for a review of the squadron and a sham fight. At daybreak a thick fog covered the bay, and the Viceroy embarked on the brig Maipo, the better to watch the manoeuvres. At eleven o'clock, as the fog commenced to lift, the sailors of the Maipo, then near to the island of San Lorenzo, saw a fine ship flying the Spanish flag skirting the sandbank of the Bocanegra. The Viceroy wished to speak her, but the commander of the brig refused to go nearer as he would
