 Following the German occupation of Denmark on 9 April 1940, Hilbert was effectively isolated from the political authorities in Copenhagen.He played a crucial role in the civil administration of the islands during the British occupation during World War II, with which he co-operated.During his tenure, the Flag of the Faroe Islands (Merkið), rather than the Flag of Denmark (Dannebrog), was flown from Faroese vessels for Allied identification purposes because of the German occupation of Denmark.