In 1890, together with Dovas Zaunius and Jonas Smalakis, Jankus founded the first Lithuanian political organization in East Prussia.
He maintained active correspondence with Lithuanian Americans and activists of the Latvian, Polish and Belarusian national movements.
For his public activities Jankus was penalized by the Prussian authorities about forty times – arrests, monetary fines, and the like.
After the Russian Empire occupied the Klaipėda Region in December 1914,[1] Jankus and his family were deported to Samara Governorate in Siberia, where his father and his youngest son Andrius died.
[1] After the Klaipėda Region was seized by Germany following the ultimatum of 1939, Jankus moved to Kaunas, the temporary capital of Lithuania.
[1] Martynas Jankus died in Germany, but expressed his will to his daughter that his body should be burned and, when Lithuania had regained independence, his ashes should be moved to the Bitėnai cemetery.
Such works included the historical novel Senutė by Vydūnas, over fifty booklets by Petras Vileišis, the first chapter of Metai by Kristijonas Donelaitis, and other works by contemporary Lithuanian authors, including Jonas Biliūnas, Lazdynų Pelėda, Gabrielė Petkevičaitė-Bitė, Antanas Kriščiukaitis-Aišbė, and others.