In the summer of 1943, during the German occupation of Estonia, together with two other members of the Estonian Students' Society, he hid the first Estonian national flag from occupying forces.
He was arrested in 1944 by the Sicherheitspolizei, the German security police, and transferred to the Stutthof concentration camp.
[2] Released in 1945, he returned to Estonia, which was by then occupied and annexed by the Soviet Union, and was then arrested by Soviet NKVD officers in Tartu the same year and placed with the gulag camp system in Kemerovo Oblast in Siberia.
[3] In 1996, he was awarded with Order of the National Coat of Arms, II class.
[4] Tammur is buried at Raadi Cemetery in Tartu.