The Huria Kristen Batak Protestan (HKBP) Church was established in Balige in September, 1917. By the late 1920s a nursing school was training nurse midwives there. In 1941, the Gereja Batak Karo Protestan (GBKP) was established. Although missionaries ceded much power to Batak converts in the first decades of the 20th century, Bataks never pressured the missionaries to leave and only took control of church activities as a result of thousands of foreign missionaries being interned or forced to leave after the 1942 invasion of Sumatra by the Japanese.