The twentieth century marked a pivotal era in global history, witnessing Western Europe's ascendancy as the dominant economic force. This transformation, rooted in Europe's industrialization over the preceding century, fully materialized after the conclusion of World War I. The Treaty of Versailles, following the war, led to the establishment of Mandates by the newly formed League of Nations, carving territories out of former German colonies in Africa and Ottoman-controlled regions in the Middle East. This act not only perpetuated the colonial civilizing mission from the nineteenth century but also laid the groundwork for what would come to be known as "the century of development."

In the aftermath of World War I, any debates regarding the merits of colonization seemed inconsequential to the Western perspective. Colonization was no longer seen as a matter of choice but as a solemn duty, a pre-existing necessity, and a moral responsibility that could neither be undone nor questioned. However, this colonial intervention and condescending paternalism now gained international sanction.

The League of Nations, as the first permanent international political institution, codified the Mandate System through Articles 22 and 23 of its covenant. While Article 22 reiterated the "sacred trust" placed upon the Western powers due to their presumed superior civilization, it also introduced the concept of development stages into the discourse of international organization.

This study delves into the internationalization of development during the twentieth century, with a focus on the pivotal role played by Western Europe. It explores how the aftermath of World War I, as epitomized by the Treaty of Versailles and the League of Nations, not only continued the legacy of colonialism but also intertwined development with international affairs. By examining the interconnectedness of colonization, moral responsibility, and international institutions, this research seeks to provide a comprehensive understanding of how development became a defining feature of the twentieth century.