Theory and concepts -- Organized rebellion and its intractable problem -- A theory of rebel fragmentation -- Rebellion in Ethiopia and Eritrea -- The Eritrean Liberation Front : "Jebha" in action, 1960-1982 -- The Eritrean People's Liberation Front : "Shaebia" in action, 1972-1991 -- The second wave of rebellion : Tigrayans, Oromos, Afars, and Somalis, 1975-2008 -- Rebel fragmentation in the broader Horn -- The long war in Somalia : the Somali National Movement, Islamic Courts Union, and Harakat al-Shabaab al Mujahidin, 1981-2013 -- Concluding thoughts.