The resistance of members of the socialist and communist workers' movements was clearly politically motivated. Dortmund was the centre of a communist resistance which continued to renew itself continuously despite arrests. At the beginning of 1945, the Gestapo arrested twenty-eight communists, who were executed in Dortmund's Bittermark forest, along with other detainees and prisoners of war in March and April. Supporters of the SPD were generally less assertive, focussing on maintaining old contacts and exchanging information. Their fragmented organisation meant that the group revolving around Fritz Henßler generally went undetected by the secret police until around 1937.
