As World War II was being fought, he also took on the responsibility of consulting in Quaternary mapping in the Latvian Institute of Mineral Resources.
He was conscripted into the Latvian Legion in 1943 or 1944, and later sent by the German Army to work as a military geologist in Italy and Germany.
[2][3] After the war Dreimanis was appointed associate professor in the Baltic University in the Displaced Persons camps at Hamburg and Pinneberg in Germany.
Several Canadian institutions called on him for his Quaternary expertise, including the Geological Survey of Canada, the Ontario Department of Mines, and the Ontario Department of Planning and Development for the St. Lawrence Seaway Authority, the Thames River Conservation Authority and various private companies.
He served as chairman of the Commission on Technical and Natural Sciences at the Latvian Cultural Foundation from 1973 to 1976.