Natural Rubber (which is still one of their primary exports), coffee, and deep water ports that were important for the region.
Natural rubber was the big one, a remarkably important trade commodity. Which was plenty enough reason to try and hold onto the country. A lot of French industry relied on the cheap, borderline slave labor plantation rubber from Vietnam.
The US toppled governments in Central and South America over fruit, for crying out loud, during the same time period. Next time you grab for a Chiquita banana, think about the colourful history of United Fruit Comnpany (the original name), and the blood that has been spilled to maintain their growing and export operations.
But as to the original question? Don't know when the first use would have been in war. I would not be surprised to find out small numbers were used in Korea, as well as the AK-47. The Soviets and Americans and Chinese have all been known to field small numbers of new weapons to client states engaged in active combat as a way of doing extended field trials.
Whatever the first use in war was, the fact they are still being used, and in relatively modern parts of the world (not just African backwaters), is a testament to the platform:
