This was German attempt by anti-Nazi resistance groups to surrender the city of Düsseldorf to the Allies and thereby avoid further physical destruction and loss of life (early April/18 April 1945).
SS units within the city were able to crush the resistance, however, and then executed a number of those involved. The murder of conscripted and impressed foreign labourers, political prisoners and other 'undesirables' by the Gestapo had already been under way since February. The effort by the resistance did accomplish one positive thing, though, as a further bombing raid on the city by 800 bombers was cancelled after the resistance had been able to contact the Americans.
Düsseldorf was captured by Brigadier General Milton B. Halsey’s US 97th Division on 17/18 April without any notable fighting.