Since the constitution of 1853, the social evolution of Argentine has been guided and carried forward by two factors, immigration and foreign capital. Under their influence, the characteristics of the prior period were gradually modified to a certain extent. The administration of Mitre struggled against the difficulties of inadequate means of communication between the distant cities and against traditional custom of guerilla warfare. Force was employed in order to remain master of the field and to break up the resistance which the men of the interior set up against the prominence of those of Buenos Ayres, and a cruel war against Paraguay was undertaken. The ability and consistency of this Argentine statesman was great. When the passions of his contemporaries had been assuaged, he became the "grand old man" of the nation, growing in stature as posterity forms its judgment on his policy. That administration, like the following one of Sarmiento, had to cope with two factors, the great uninhabited tracts of land and the survival of ancient custom. On the one hand the different Argentine regions lived in isolation from one another, communication between them being difficult; on the other hand there still survived the custom of local chieftainship and of the constant and armed movements of different political factions, who would set out upon guerilla forays on any pretext whatsoever, raising their banners on high as though their behavior was patriotic and praiseworthy, whereas it was but the vicious habit of a barbaric and backward age. The administration of Avellaneda continued the task of combating such tendencies by the establishment of the telegraph which would unite all these centers to each other; by the construction of railroads to facilitate communication; and by the encouragement of European immigration for purposes of settlement and in order to mix other races with that of Argentine and so modify its political idiosyncracies by more conservative standards and interests. The conquest of the Patagonian wilds, with the final subjugation of the warlike native tribes of the south, opened and ushered in an era in the Argentine evolution. This occurred contemporaneously with the historic solution of the problem of federalism versus centralism, which silenced forever the old antagonism between the inhabitants of the metropolis and those of the provinces.