I was just writing a post (which I haven't actually posted yet) mentioning the Fascist invasion of Ethiopia and the their comically flimsy justification (or the closest thing to one they ever bothered giving) for attempting to annex Ethiopia- to suppress slavery. Never mind the fact that slavery's persistence in Ethiopia wasn't for the lack of trying- Tewodros II outlawed slavery in the 1850s (before the US for that matter), albeit to little effect, as were the efforts of his successors.
But to get to the question, my mind wandered to another African war
genuinely fought to suppress slavery, the
Anglo-Zanzibar War. Better known (or in most cases only known) for its record-holding brevity than its causes, the "war" was initiated by Britain strictly over the matter of ending slavery in the island Sultanate.
The Wikipedia article rather glibly states the war was caused by the accession of a new Sultan instead of one "who was more favourable to British interests" without bothering to mention what those interests were. It does seem difficult to believe Imperial Britain would wage a war for such "humanitarian" purposes, so difficult, in fact, that I tried to find an alternate explanation, to no avail.
So, a war of aggression fought by a colonialist empire against a far smaller African nation... to end slavery. What do you make of it?