[7] Both Grepp and the other Norwegian correspondents in Spain, like Nordahl Grieg and Nini Gleditsch, sympathized with the Republican cause in the war.

[7] Gleditsch and Grepp helped organize a large-scale aid effort for Spain, based around the Norwegian labour movement.

[9] In January and February 1937 she visited Málaga, together with Hungarian journalist and reporter for the British daily newspaper News Chronicle, Arthur Koestler.

[5][10] She and Koestler took shelter with the eccentric 72-year-old Sir Peter Chalmers Mitchell, who had stayed on in Málaga "to protect his house and servants" while his compatriots fled to Gibraltar.

She visited the Republican Basque Army defensive line called the Iron Belt, and experienced the Battle of Bilbao.

[1] Grepp's work has since been largely forgotten, her fellow journalist Lise Lindbæk instead being commonly seen as Norway's first female war correspondent.