a turbulent first few years

Although unified as a single nation at independence, the south and the north were, from an institutional perspective, two separate countries. Italy and Britain had left the two with separate administrative, legal, and education systems in which affairs were conducted according to different procedures and in different languages. Police, taxes, and the exchange rates of their respective currencies also differed. Their educated elites had divergent interests, and economic contacts between the two regions were virtually nonexistent.

Despite the difficulties encountered in integrating north and south, the most important political issue in postindependence Somali politics was the unification of all areas populated by Somalis into one country; a concept identified as pan-Somalism, or Greater Somalia. Somalia laid claim to Somali-populated regions of French Somaliland (later called the French Territory of the Afars and Issas, and Djibouti after independence in 1977), the northeastern corner of Kenya, and the Ogaden, a vast, ill-defined region occupied by Somali nomads extending southeast from Ethiopia's southern highlands that includes a separate region east of Harer known as the Haud. The uncertainty over the precise location of the frontier between Ethiopia and the former Italian possessions in Somalia further complicated these claims. Preoccupation with Greater Somalia shaped the character of the country's newly formed institutions and led to the build-up of the Somali military and ultimately to the war with Ethiopia and fighting in the Northern Frontier District (NFD).

The national flag featured a five-pointed star whose points represented those areas claimed as part of the Somali nation, those being the former Italian and British territories, the Ogaden (in Ethiopia), Djibouti (a small, independent republic), and the NFD. Moreover, the preamble to the constitution approved in 1961 included the statement, "The Somali Republic promotes by legal and peaceful means, the union of the territories." The constitution also provided that all ethnic Somalis, no matter where they resided, were citizens of the republic. The Somalis did not claim sovereignty over adjacent territories, but rather demanded that Somalis living in them be granted the right to self-determination. Somali leaders asserted that they would be satisfied only when their fellow Somalis outside the republic had the opportunity to decide for themselves what their status would be.

In 1961 Somali representatives from the NFD demanded that Britain arrange for the NFD's separation before Kenya was granted independence. The British government’s investigation indicated that separation from Kenya was almost unanimously supported by the Somalis and their fellow nomadic pastoralists, the Oromo, which represented a majority of the NFD's population.

The denial of Somali claims led to growing hostility between the Kenyan government and Somalis in the NFD. Adapting easily to life as shiftas, or bandits, the Somalis conducted a guerrilla campaign against the police and army for more than four years between 1960 and 1964.

Somalia refused to acknowledge in particular the validity of treaties defining Somali-Ethiopian borders. Somalia's position was based on three points: first, that the treaties disregarded agreements made with the clans that had put them under British protection; second, that the Somalis were not consulted on the terms of the treaties and in fact had not been informed of their existence; and third, that such treaties violated the self-determination principle.

Obviously… this did not go over well with Ethiopia, which was itself, struggling for unification.

Sources are here, here, here, here, here, here, and here.