Mangaradja Soeangkoepon was born on 26 December 1885 into an aristocratic Angkola Batak family in Sipirok or possibly in Padangsidempuan; his father was a local district head.
[1] In 1915 he returned to government service and held various administrative roles in Tapanoeli Residency and East Sumatra, including time spent on the local council of Pematangsiantar and Tanjungbalai.
Soeangkoepon was a member of it along with R. P. Suroso, Dwijo Sewoyo, Mukhtar, Datuk Kayo, Sutadi and Pangeran Ali; their stated platform was for Indonesia to become independent from the Netherlands as quickly as possible, and to maintain a common front against divide-and-conquer tactics.
[6] During that session he sat on a committee for educational reform with Loa Sek Hie, Oto Iskandar di Nata, and a number of other members.
[24] That summer he also publicly accused the government of having lowered the status of the Volksraad over the previous decade and in particular disregarding the wishes of Indonesian members.
[25] In November 1939, partly influenced by the outbreak of World War II, he and his group sent a petition to the Tweede kamer in the Netherlands calling for the establishment of a fully-formed, directly elected parliament in the Indies.
[26][27] The petition stated that twenty years had passed since the Netherlands' 1918 declaration of moving towards self-government and called upon the government to make good on its claims to support reformist nationalists while rejecting radicals.
[26][27] It also noted that the Indies was quite remote from the Netherlands and that they could not necessarily expect support, military defense or coherent directions while Europe was in the middle of a war.
[27] In 1940 he was vilified in the colonial press for his statement in the Volksraad that the Dutch government and European officials only knew the outer regions of the Indies through the collection of taxes, which he characterized as causing hunger and deprivation to the populations there.
[31][32] In November 1943, in an effort to give some limited autonomy to Indonesians, the East Sumatra People's Council was made with a plan to have yearly elections.