March 4, 1913 – March 4, 1921
The "Otranto Disaster" took place when the "SS Otranto" was rammed by another troop ship off the coast off the Isle of Islay.
I'd say that they got it from exploration, really.
Religious and political conflicts diminished
The climate of East Africa is rather atypical of equatorial regions. Because of a combination of the region's generally high altitude and the rain shadow of the westerly monsoon winds created by the Rwenzori Mountains and Ethiopian Highlands, East Africa is surprisingly cool and dry for its latitude. If it is different maybe it will took long before it will develop. It developed because it was a strategic location for trade with other countries. If its is an inland or mountain area, it would not be the center of trade so the development will much be slower.