During the Algerian war (1954–1962), beside the war events proper, another conflict took place: a diplomatic and technocratic battle for the possession of Saharan oil resources in the name of national energy security. Its main actors were France, Italy, the US, and Algerian independence fighters. In the case I analyse in this paper, I show that the three Western-block countries used their local knowledge of the subsurface given by the collaboration of the three elements of: (1) geoscientists, (2) their national oil companies, and (3) their respective diplomatic bodies, in order to carve out a prominent place for themselves in the exploitation of Saharan resources. Algerian nationalists also succeeded in benefiting from this knowledge. I argue that this struggle for natural resources in a post-independence scenario, and the corresponding role of the geosciences in it, significantly contributed to influence the final configuration of the postwar Algerian hydrocarbon sector.