In 1887 Hirth was assigned to Uganda, arriving at
Bukumbi on the south shore of
Lake Victoria in October 1887. He was given the task of running a school of catechists and a minor seminary. Hirth lived at the
Kamoga mission for three years while directing an orphanage of children of former slaves whom the White Fathers had freed and converted to Christianity. At the start of 1890 his superior as Vicar Apostolic, Léon Livinhac, heard he had been appointed Superior General of the White Fathers, and on 25 May 1890 he consecrated Hirth as his successor. Hirth was appointed Titular Bishop of Teveste and Vicar Apostolic of
Victoria Nyanza (now the
Diocese of Mwanza) on 4 December 1889. He was consecrated bishop on 25 May 1890. This area included parts of modern-day
Uganda,
Rwanda,
Burundi and northern
Tanzania. Hirth set the objective of making
Buddu a Catholic country by the end of 1892, unleashing a surge of building and evangelical activity. For several years he traveled through his huge vicariate visiting the scattered missions. The missionaries had to deal with rivalries between the local rulers, who were forming alliances with the rival colonial powers of Germany and Britain, and at times with hostility from the colonial authorities. A civil war broke out in Buganda in 1892, during which the Catholic camp was totally defeated. The war pitted supporters of the French Catholic missions against supporters of the British missions in Buganda, backed by a small force of Sudanese soldiers under Captain
Frederick Lugard of the Indian Army. Lugard's
maxim gun proved decisive. Hirth and the White Fathers moved to the
Bukoba kingdoms of Kiziba and Bugabo in 1892 with about fifty
Baganda Christian converts. In December 1892 they founded a mission at
Kashozi, in what is now the extreme north of Tanzania. In 1894 the diocese was split into Southern Nyanza, south and west of Lake Victoria, an eastern portion called "Upper Nile" that was given to the English
Mill Hill Missionaries, and a northern portion called "Northern Nyanza" that covered the south and west of today's Uganda. Hirth was appointed vicar Apostolic of
Southern Victoria Nyanza on 13 July 1894. He made Kashozi his Episcopal See. Hirth moved to
Rubya, where he had founded a seminary, and was personally involved in training future priests for Bukoba and Rwanda. By 1906 he had five mission posts in the Bukoba region and three in the Mwanza region.
Joseph Sweens was appointed
coadjutor bishop to Hirth and reached South Nyanza in April 1910. Hirth returned to his old residence at Kashozi, leaving Sweens to live at the seminary of Rubya. The
Catholic Encyclopedia of 1912 said the vicariate had about 2,500,000 pagans, 7,000 Catholics, 12,000 catechumens, 30
White Fathers; 23 lay brothers and six Missionary Sisters of Notre-Dame-d'Afrique. There were 15 mission stations and 20 churches or chapels. ==Kivu==