Harris Gaylord Warren was, by common consent, the father of Paraguayan studies in the United States. His broad-ranging activities —from diplomatic undertakings in South America to military service in Italy to administrative and scholarly work at various North American universities—marked him as an historian of rare depth and insight. Not commonly known is that Dr. Warren began his career as a historian in the 1930s as a borderlands specialist. The Sword was their Passport: A History of American Filibustering in the Mexican Revolution (Baton Rouge, 1943) is yet recognized as the definitive work on North American adventurers in that turbulent era. As an officer in the United States Army in World War II he was selected for various military history projects. After the war Dr. Warren returned to teaching and then administration. At that time his publications ranged from texts to Herbert Hoover and the Great Depression, (New York, 1959).

The Evueví (commonly known as the “Payaguá”), a Guaycuruan tribe in southern South America, dominated the Paraguay and Paraná rivers for more than three centuries. Non-sedentary, similar in nature to the Chichimecas of northern Mexico and the Araucanians of southern Chile, the Evueví were riverine Indians whose life was seriously disrupted by the westward expansion of the Spanish and Portuguese in the Gran Chaco and Mato Grosso regions. This study will identify Evueví strategies for survival and analyze the nature of intercultural contact between the Indian and Spanish cultures. A study of the ethnohistory of the Evueví contributes to an understanding of the cultural adaptation of a non-sedentary indigenous tribe on the Spanish frontier whose salient features were prolonged Indian wars, Indian slavery, and missions. Such an analysis also provides an opportunity to analyze European attitudes and perceptions of a South American indigenous culture. Unlike other Amerindians, the unique characteristic of the Evueví was that Europeans perceived them as river pirates during the colonial era.

The great economic and political changes in the Río de la Plata of the late 1700s penetrated not only Buenos Aires and the interior of present-day Argentina, but upriver the hitherto neglected province of Paraguay shared the reforms of the Intendant system and economic liberalization. Those changes, along with the expulsion of the Jesuits, produced a shift in the economy of this region from the Paraná-Tebicuary area to the northern frontier of that province. The impelling economic motive for that shift was the north's greater ability to meet the demand for Paraguay's primary export, yerba mate. By the 1780s, northern Paraguay experienced a greater exploitation of yerbales, both to the benefit of independent entrepreneurs and government revenues.

The creation of the Viceroyalty of the Río de la Plata in 1776 by Charles III of Spain and his Edict of Free Commerce two years later brought unprecedented commercial prosperity to the port cities of Buenos Aires and Montevideo. Unlimited trade was now allowed between this region of South America and Spain. Exports—mainly silver from Alto Perú and pastoral products from the pampas—flowed in ever greater volume to the Iberian Peninsula. In return, merchants of the estuary received from Spanish commercial houses European manufactures and luxury items. This trade which spanned the South Atlantic depended upon a complex web of credit and merchant associations between the Old World and the New, and also upon the unobstructed traffic of Spain's merchant marine. In the 1780s and early 1790s with the Empire at peace Platine commerce contributed to both government revenues and the growth of a dynamic immigrant merchant community recently arrived from northern Spain. By 1794 the booming trade of the new viceroyalty justified the creation of the Real Consulado de Buenos Aires, essentially an official merchants guild to regulate the business affairs of this region.

Although the study of the liberal republic (1870-1936) could shed considerable light on the overall pattern of political development, this period has remained one of the most under-studied and undervalued of the already under-researched history of Paraguay. In an attempt to fill that lacuna—albeit partially—this article reexamines the available data, discusses new evidence, and reinterprets the period with different theoretical categories. In this manner, it seeks to answer the question of why, in spite of a relatively favorable ideological environment, liberal democracy failed to consolidate and how this failure eventually opened the doors to the authoritarian regime of General Alfredo Stroessner.