WarSampo Knowledge Graph includes harmonized data of different kinds concerning the Second World War in Finland, separated in different subgraphs representing events, actors, places, photographs, and other aspects and documentation of the war. The data covers the Winter War 1939-1940 against the Soviet attack, the Continuation War 1941-1944 where the occupied areas of the Winter War were temporarily regained, and the Lapland War 1944-1945, where the Finns pushed the German troops away from Lapland. To test and demonstrate its usefulness, this Knowledge Graph is in use in the semantic portal WarSampo, explained in more detail in the project page. Example SPARQL queries for the data: Events, photographs and articles that are situated in Vyborg Casualties of the 1st Division and its subunits in the time interval 13.2.-13.3.1940 by place and date WarSampo knowledge graph version history: 1.0.0, November 2015: Initial public release 1.1.0, November 2017: War cemeteries addition 2.0.0, May 2018: Backwards-incompatible URI changes 2.0.1, November 2019: Updated schema and VoiD descriptions 2.1.0, November 2019: Prisoners of war addition Version 2.1.0 contains 14,322,426 triples. To combine the files into a single Turtle file on a Linux system: find . -mindepth 2 -name "*.ttl" | xargs cat >> warsampo.ttl