The commanders of the cities of _Imperial_ and _Valdivia_, both of which were closely besieged by Caupolican, demanded succours of Villagran, who, notwithstanding his late losses, was still in a position to send them a sufficient number of troops for their defence. Under these circumstances, the Araucanian general, despairing of gaining possession of these places, retired with his forces to join Lautaro. Villagran taking advantage of the retreat of the enemy, ravaged the country in the neighbourhood of _Imperial_, to which place he transported all the provisions that remained. To these calamities of war was at this time added pestilence. In the above-mentioned incursions made by Villagran, some Spanish soldiers conveyed for the first time to the Araucanians the terrible contagion of small-pox, which made enormous ravages amongst them. It is said that in one district, containing twelve thousand persons, not more than one hundred escaped with life. [Sidenote: 1555.] Whilst the duty of opposing the Araucanians demanded all the efforts and attention of Villagran, that officer was on the point of being compelled to turn his arms against his own countrymen. Valdivia had left behind him written instructions, to be opened in the case of his death. By these his succession devolved in turn on Alderete, Aguirre, and Villagran. The first being absent in Europe, and the second in _Cujo_, the command, as has been said, was assumed by Villagran. Aguirre, however, on learning the death of Valdivia, quitted _Cujo_, and with sixty men returned to _Chili_, determined to possess himself of the government. Civil war was on the point of breaking out; but with more self-control and self-denial than was usually to be found amongst Spanish conquerors, both aspirants agreed to submit their respective pretensions to the Royal Audience of _Lima_. This court, which had at this time jurisdiction over the whole of South America, left at first the question in abeyance, but on reflection confirmed Villagran in the command, ordering him at the same time to rebuild _Conception_. This measure was carried out by him in opposition to his own judgment. The natives of the country, indignant at the renewed prospect of a foreign yoke, had recourse to their protectors, the Araucanians, who sent to their assistance two thousand men under the command of Lautaro. The young general passed the _Bio-bio_ without delay, and was met by the Spanish force in the plain. On the first encounter, the citizens, struck with panic, returned to the fort with such precipitation that the Spaniards entered with them, killing a great number. The remainder dispersed either on board ship or into the woods, finding their way as best they could to _St. Iago_. Lautaro again burned the city and returned to his usual station.