The ground plan of the city of Buenos Aires resembles a chessboard, all the streets running either perpendicular to the course of the river--that is, due east and west, or parallel with it--that is, due north and south, crossing each other at right angles at distances of 150 varas. The city is thus cut up into square blocks of houses, each block being styled a manzana. Between the two streets which run out westwards from the Plaza Mayor, the two central streets of the city, and ten squares distant from this Plaza, one entire block was left vacant of buildings, and was in those days a mere open space of waste ground. At the northern corner of the eastern side of this vacant space stood the house of Don Isidro Lorea. Don Isidro was a captain in the city militia. On the morning of the 26th June, when the English were advancing upon the city, he had mustered his men, had marched them to the fort, and had placed himself and them at the orders of the Marquis of Sobremonte. Later on he had marched them into the suburbs, and upon the near approach of the invaders had fled with them in confusion and dismay back to his own home. Don Isidro's ideas on military matters were vague in the extreme; previous to that day he had never seen a gun fired in anger; but he was no coward, and when the first effects of his terror had passed over he bitterly upbraided himself for his pusillanimity. Tears had stood in the eyes of his wife, Doña Dalmacia, as she had watched him march away, and she had spent the time during his absence on her knees in a neighbouring church, praying earnestly for his safety; but when he returned to her safe, sound, and vanquished, then those same eyes looked upon him in utter scorn and contempt, and his heart quailed within him even more than it had quailed at the sight of the British bayonets. During those days of shame and despair which followed, Don Isidro nourished within his breast wild schemes of revenge and retaliation, and he eagerly associated himself with those who planned together the destruction of the small British force which held their city in thrall. Yet weeks passed and nothing was attempted. As Don Gregorio Lopez had told them, their first necessity was a leader, and he to whom they all looked as a leader had gone from them. Liniers had gone to Monte Video to seek the aid of Huidobro, who commanded in that city, telling them to make what preparations they could in the meantime, and that he would look to them for help on his return.