Pre-Independence
As Independence approached in the 1940s-1950s, it was clear that the Baganda (the largest ethnic group) wanted extensive autonomy in Uganda, and the Buganda King's party Kabaka Yekka ("The King Only") emphasised this desire. However this was not favoured by most Ugandans of other tribes and amongst some Buganda educated elite who formed an alternative party, the Democratic Party (Uganda) to aspire for national unity. Although unpopular in Buganda, the Democratic Party had widespread support in the rest of the Bantu-speaking South.
Into this void, there emerged an alternative - the Uganda National Congress (UNC). Although led by a Northerner (Milton Obote), the UNC appeared more modernist and accommodating and attracted many Southerners particularly in the East. The UNC formed a number of alliances with other parties and emerged as the Uganda People's Congress (UPC). The three parties (Kabaka Yekka, UPC and the Democratic Party) contested the first pre-Independence election.
As expected, Kabaka Yekka won most of the seats in Buganda and the UPC won most seats in the North and East. However the Democratic Party (DP) led by Benedicto Kiwanuka emerged as the largest single party. Kiwanuka was on the verge of becoming the first Prime Minister of independent Uganda when he was thwarted by a surprising alliance between the UPC and Kabaka Yekka.
The Kabaka was afraid that DP would remove the Monarchy in favour of a more modern-looking Uganda. As for the UPC, Milton Obote, realising he had lost the election, saw the alliance as the way to power. In return Obote offered the Kabaka a ceremonial role in the new administration and the retention of all royal powers. The UPC/KY alliance thus formed Uganda's first government with Milton Obote as Prime Minister.
Read more about this topic: Uganda People's Congress