As what was then the second most populous French-speaking country in the world (it has subsequently come to have a larger population than France) and the most populous one in sub-Saharan Africa, Zaire was of great strategic interest to France. During the First Republic era, France tended to side with the conservative and federalist forces, as opposed to unitarists such as Lumumba. Shortly after the Katangan secession was successfully crushed, Zaire (then called the Republic of the Congo), signed a treaty of technical and cultural cooperation with France. During the presidency of Charles de Gaulle, relations with the two countries gradually grew stronger and closer. In 1971, Finance Minister Valéry Giscard d'Estaing paid a visit to Zaire; later, after becoming president, he would develop a close personal relationship with President Mobutu, and became one of the regime's closest foreign allies. During the Shaba invasions, France sided firmly with Mobutu: during the first Shaba invasion, France airlifted 1,500 Moroccan troops to Zaire, and the rebels were repulsed; a year later, during the second Shaba invasion, France itself (along with Belgium) would send French Foreign Legion paratroopers (2nd Foreign Parachute Regiment) to aid Mobutu.