Mordechai Abir's Ethiopia and the Red Sea probably should have been given an alternative title. Besides one chapter on the role of the Red Sea and the Indian Ocean in Ethiopia's trade networks and Ottoman versus Portuguese conflicts for dominance of the Red Sea, Persian Gulf, and Indian Ocean, this book is mostly a narrative history of the Solomonic dynasty of Ethiopia from it's expansion in the 1300s to the era right before the Gondarine period. So, Abir's study builds on earlier research by the author and the scholarship of Tamrat and other Ethiopianists to analyze why the Solomonic dynasty failed to establish a more integrated, centralized state in the Horn of Africa. Lacking familiarity with most of the sources utilized by Abir, we cannot determine how accurate or misleading some of his interpretations are, but he did not really utilize Ethiopian sources in Ge'ez so one cannot help but think that skews his interpretation of certain figures, like Susenyos or the conflicts within the church between the two monastic orders over theological debates.
Besides disastrous events like the jihad of Ahmad Gran and the Oromo migrations which continued with very little Ethiopian resistance from the royal court, Abir outlines a plethora of additional factors behind the failure of the Solomonic state to develop an effective, centralized polity capable of integrating or resisting Oromo migration, modernizing, or expanding its influence in the Horn. These include an elite Church dependent on appointed abuns from Egypt, little sustained efforts at evangelizing and integrating conquered peoples, tensions between the Amhara and the northern population of Tigre, regional lords and nobility using succession and factions in the royal court to challenge or revolt the emperor, attempted military and administrative reforms that, in some cases, aided and abetted Oromo expansion into provinces of the empire. The particularly long reign of Sarsa Dengel seems to be a great example of wasted opportunities for reform and centralization, processes that could have helped Ethiopia resist or integrate the Oromo and build a "modern" state beyond the "feudal" military-administrative structure Abir describes. It's hard for this blog to not read Abir's chapter on Sarsa Dengel and not think of the opposite trends in Borno under Idris b. Ali, or Idris Alooma, who appeared to have been far more effective at defending and expanding the borders of Borno while also promoting a monotheistic religion that must have served an integrative function in its vast domains.
Of course, the most interesting and perhaps too brief chapters analyze Susenyos and the Jesuits. Susenyos is depicted as someone who believed in the superiority of Catholic or European civilization and wanted to use it as a way of modernizing the state. Earlier rulers, who had expressed an interest in European military technology and artisans, were supposedly not modernizers, despite some of them attempting various administrative and military reforms with Mamluk or European aid. Susenyos, however, was pressured by the Jesuits into thinking Portuguese-Spanish military aid would flow to Ethiopia if he agreed to impose Catholicism as the official religion. With their aid, presumably Susenyos could have created a state based on different lines, reclaimed territories lost to the Oromo, and "modernized" Ethiopia. Abir presents this as an early attempt by a non-European state to modernize long before the more famous examples of the Middle East and Egypt, but one which Ethiopia was not prepared for due to the very unlikely chances of a Portuguese military presence or expedition and the fierce resistance to the Jesuits from members of the emperor's inner circle, the native religious hierarchy, Jesuit dogmatism attacking local culture and the "feudal" lords opposed to political centralization. Since more recent scholarship has focused on the period of the Jesuit mission, we shall return to this period in Ethiopian history and some of the conclusions reached by Abir of the Gondarine period as one of decline or, perhaps, failure.