On the outbreak of the First World War he was attached to the torpedo-boat Commandant-Rivière on operations against the Austro-Hungarian fleet in the Adriatic, particularly during the evacuation of the Serbian Army.

In May 1929 he was put in command of the 11th Torpedo Boat Division in the Mediterranean on board the Alcyonand reveals himself as "an exceptionally talented officer and a brilliant maneuverer".

At dawn on 27 November that year, when German forces arrived in the Toulon arsenal, he ordered its cruisers to scuttle themselves.

[4] From then onwards "he never stopped struggling at all times against the German and Italian armistice commissions, sabotaging any work in the arsenals that would assist the enemy and saving personnel in the naval and colonial ministry from being sent to Germany.

After crossing into Switzerland, Pétain and his circle voluntarily surrendered at the border post at Valborde a few days later.

He was found guilty of crimes against state security and of 'indignité nationale' by that court and condemned in his absence to 10 years' imprisonment and national degradation.