It was morning in East Africa. The day was May 26, 1886, and along the shore of Lake Victoria the mist still hung thickly in the jungle undergrowth, although the sun had risen well above the horizon. The night-time cacophony of wildlife had long since subsided, and the land was quiet except for the buzzing of insects and the murmur of hushed voices.In a wide clearing on a hill above the lake, a dramatic scene unfolded. Uganda's King Mwanga was holding court in the open-air gathering place in front of his temporary residence, his royal palace being under repair after...