The book Marx and Diplomacy explores for the first time in international literature Marx's work in diplomacy, utilizing all his texts, his correspondence, hundreds of recently published manuscripts, as well as the minutes of the meetings of the First International.

The book shows how Marx and Engels move from analyzing developments in Europe to those of the international system. It also presents the controversies that existed in the Left of their time regarding international problems, especially concerning liberalism, tsarism, Bonapartism, anarchism, as well as Proudhon's rejection of their views on patriotism.

Marx thoroughly engages with the diplomacy of the great powers of the time, with developments at the fringes of Europe, such as the French occupation in Spain and Portugal, the dismemberment of Poland, the state of the colonial system, and the Eastern Question.

His concern is the need for the democratic and labor movement to have its own foreign policy, to learn the secrets of diplomacy, to understand the significant international events of the time, to illuminate the great popular uprisings with immediate international significance, such as those in Poland, China, and India, and the Commune in Paris.

Marx analyzes the international system and its structures. He defines the dialectical relationship between foreign and domestic policy, economy and politics. He shows the autonomy of the former from the latter and their feedback loops. The role of the state and patriotism in international relations. The presence of three international currents of emancipation: the labor movement, democratic "Agrarian Democracy," and the national liberation movement.

And then, he establishes principles and criteria for a progressive foreign policy, which, along with his analyses, form the foundations for a dialectical-materialist theory of diplomacy and international relations.