midnight
For from the commencement of the siege the whole population had been rationed , all the provisions in the town had been handed over to the authorities for equal division , and every house , rich and poor , had been rigorously searched to see that none were holding back supplies for their private consumption . Many of the cattle and horses had been killed and salted down , and a daily distribution of food was made to each household according to the number of mouths it contained . Furious at the successful manner in which the party had entered the town on the 28th of January , Don Frederick kept up for the next few days a terrible cannonade against the gates of the Cross and of St. John , and the wall connecting them . At the end of that time the wall was greatly shattered , part of St. John 's gate was in ruins , and an assault was ordered to take place at midnight . So certain was he of success that Don Frederick ordered the whole of his forces to be under arms opposite all the gates of the city , to prevent the population making their escape . A chosen body of troops were to lead the assault , and at midnight these advanced silently against the breach . The besieged had no suspicion that an attack was intended , and there were but some forty men , posted rather as sentries than guards , at the breach .