Decolonisation-era Africa is fascinating, to me, as well as the alliances between rogue regimes. The two come together in a spectacular (and somewhat sinister) collision with the "official unofficial" alliance between Rhodesia (1965-1979/80), and Apartheid South Africa (~1948-1994).
Though the two countries were united by a common economic and defensive interest, they certainly had their differences. South Africa was staunchly and perpetually 'Apartheid'. Its entire society was dominated by the idea of an entrenched white ruling class. Rhodesia, though often accused of being an Apartheid nation, allowed blacks to serve in the military (even rising to become commissioned officers), study in higher education facilities, and even serve in the government. In fact, Ian Smith himself privately admitted that he felt majority rule was inevitable, and that it should happen on a timeline of 10-15 years, rather than the oft quoted "not in 1000 years" stance he took, in public. Of course - there was a great deal of racism and inequality in Rhodesia, too. Let's not ignore the fact. I simply wanted to point out that the two apparently similar nations were, in fact, ideologically different.
Anyway - my idea is that we have a POD around 1978/79, wherein (as OTL) Rhodesia is beginning to make compromises, and open negotiations with the rebels it has been fighting for over a decade. ITTL, however, South Africa - perhaps whipped-up into a Cold-War frenzy through media spin and the fears of yet another border with a hostile ("terrorist", as they often called independent African states) nation - makes a pre-emptive military intervention within Rhodesia. Either with the aim of annexation (as it did with OTL Namibia in 1915, before being forced to relinquish it), or to prop-up a puppet-state.
What do you guys think? Interesting TL? What would the effects be? Would Britain immediately declare war (considering Rho/Zim to be under its protection), or stand by in the hopes that South Africa would further distance itself from the international community, and that they could kill two birds with one stone? What would the reaction be like in Rhodesia/Zimbabwe? Would the whites welcome the change? Sounds silly, of course, but I actually know a white Zimbabwean whose family left for England in '80, because they couldn't stand the thought of moving to South Africa (what with its treatment of its native population).
So yeah. Thoughts?