FWI Challenge: Create an "African Union"

Here's the challenge: Create a plausible scenario in which various countries in Africa form an African counterpart to the European Union or NATO.

You have a lot of freedom in this challenge. Your hypothetical "African Union" can comprise of nations from North Africa, Southern Africa, the Maghreb, Middle, Eastern or Western Africa, or (if you're really gutsy), a combination of different regions.

You can form this union through the peaceful formation of political, economic and/or military alliances, OR through military conquest.

You only have one rule: go the military conquest route, you are forbidden from using nukes (Pretty sure only a handful of African countries have nukes, or none at all).