Occupation by Italy then Germany

On 3 September 1939 France declared war against Germany. Two days later, in application of article 4 of the treaty of 1918, 300 French soldiers were posted to Monaco. During the "Phoney War" life in Monaco returned to normal to the point that society events started up again although the supply of provisions remained a real problem. Anti-Semitic legislation inspired by the Vichy Regime was introduced much later than in France and although deportations did take place so did various acts to protect the Jews of the Principality.

On 11 November 1942 the Italian army entered the Principality, reinforcing the beaches with barbed wire in order to protect against an Anglo-American landing from North Africa. With the population of the Principality oppressed by war, the sovereignty of the Prince was challenged. Various acts of resistance followed and information networks were set up in Monaco. On 9 September 1943, the day after the surrender of Italy, the Italian soldiers left Monaco, to be replaced the following day by Germans.

Monaco was seen as a great prize by Germany; a consulate was established in 1943 and cooperation in radio news began between France and Germany in the form of Radio Monte-Carlo.  Between January and March 1944 round-ups increased.

 After the Allied landed in Provence on 15 August 15 1945, Monaco is liberated on the 3rd of September.