In 1920, he was a professor at the École supérieure de la Marine in Toulon, in 1927, captain, Esteva decided to follow a pioneering path in the nascent naval aviation, an original choice for an officer of this rank.

His stay in the Pacific led him to regularly visit the British bases of Hong Kong and Singapore as well as to fully appreciate the rise in power of the Imperial Japanese Navy.

In Paris, he was taken to the Ritz (then partly occupied by the Luftwaffe) in order to be put there under house arrest while waiting for the German authorities to rule on his fate.

German Foreign Minister Joachim von Ribbentrop sent him a message of sympathy and thanked him for having "facilitated the conduct of the war by the Axis powers".

In North Africa, however, a War Council, chaired by General Henri Giraud, on 15 May sentenced Esteva to the death penalty in absentia.

Accused of delivering wheat to the Italian army in Libya, granted facilities to Axis troops to establish themselves on the coast and Tunisian airfields after the Allied landing in 1942, recruited workers and combatants in a Phalanx African in the service of Germany, manifested on several occasions his sympathy for the German cause, he sketches the so-called "double play" defense, often repeated later.

Thus, he affirms that in spite of his fidelity to Pétain, it was not a blind discipline which guided him, that he only composed with the enemy to save the essential: his departure would have put Tunisia under Italian control, the delivery of wheat to the Italians in Libya was compensated by identical shipments to the French populations, he sabotaged the recruitment of the African Phalanx, he did not have enough troops, with 12,000 men, to oppose the Axis forces, the Allies being too far away.

Leaning, in The Great Trials of Collaboration, on Esteva's journey, and in particular his Tunisian period and his trial, Roger Maudhuy considers, on the basis of several testimonies, that Esteva helped the local Resistance and provided false identity documents to members of the Jewish community, communist activists, German escapees and Alsatian refugees.

General de Gaulle, in his War Memories, commented on this trial in these terms: "Admiral Esteva was sentenced to imprisonment.

At the end of a career which, until these events, had been exemplary, this old sailor, led astray by false discipline, found himself an accomplice, then a victim, of a harmful enterprise."