He was a trusted advisor to the King during the difficult later years of the Mussolini régime, and played a central role in the final meeting of the Grand Council that took place overnight on 24/25 July 1943, and in the frantic consultations that ensued.

Pietro d'Acquarone retired from active military service in 1924, attaining the rank of Brigade General,[7][8] in order to devote himself to managing the family business, which by this time it is described in sources as a "finance company" ("Società anonima finanziaria").

By 1933 the criteria and usages had changed: the record spells out that D'Acquarone qualified for senate membership under condition number 21, because he was one of those who for each of the precious three years had paid at least three thousand lire in direct taxation, either personally or else in respect of the business(es) he owned.

The king's confidence in his administrative skills and good judgment more broadly only grew, meaning that behind the scenes Pietro d'Acquarone had become the monarch's most respected and trusted adviser.

Through his contacts with dissident fascists, disillusioned army commanders, Italian industrialists as well among known anti-fascist circles, he was able to ensure that the king was as well informed about opinions in the country as any member of the Grand Council when he finally dismissed Mussolini from his post.

After February 1943, when Ciano was transferred from the foreign ministry to the Italian ambassadorship at the Vatican, d'Acquarone was encouraged to hope that the development might open the way for less blinkered elements in the Fascist movement to persuade Mussolini of the intensifying dangers represented by the "Axis Alliance".

Records of d'Acquarone's contacts with Dino Grandi during the first half of 1943, provide evidence of his attempts to persuade leading fascist party members in the government to take a more assertive line.

[4][17] The historian Claudio Pavone, who made a close study of the period, suggested that Victor Emmanuel's evolving strategy after 1940, whereby the monarchy should progressively distance itself from the fascist government and, in particular, from the disastrous military alliance with Germany, was based on ideas hammered out jointly by the king and d'Acquarone.

Their strategic goal would be "fascism without Mussolini", a non-fascist government of technocrats backed by leading anti-Mussolini army officers, which could create the conditions for as prolonged a period as of resistance as might prove necessary for the political forces of antifascism.

In the event Badoglio would take over leadership of the government following the removal of Mussolini, although following the liberation of Rome in June 1944, at the urgent prompting of the American and British authorities he would be replaced by Bonomi in the role.

As early as 26 May 1943 d'Acquarone had the first in a series of meetings with Ivanoe Bonomi, who presented himself as the representative of a number of antifascist politicians, many of whom had been politically engaged before 1922, and others of whom were already enjoying the discrete hospitality of the pope at the seminary complex attached to the Archbasilica of Saint John Lateran, in the eastern part of the city centre.

Mussolini was made aware, by his newly appointed police chief, of the complex network of contacts that d'Acquarone was operating on behalf of the king, but seems to have been unwilling to attach too much importance to the matter.

There are also indications that d'Acquarone, during this period, was serving as a go-between for the king in communications with his daughter-in-law, the Princess of Savoy who had spent much of the First World War as a Belgian royal evacuee at the Brentwood Ursuline Convent High School in Brentwood, England and whom the king suspected - correctly - of conducting a personal foreign policy that aligned more closely with the needs of the Belgians and the wishes of the Americans than with the interests and international policy of Italy.

A temporary royal court was then established in Brindisi, while the slow and bloody, but by this stage seemingly inevitable, liberation of the rest of Italy from south to north, by Italian partisans in partnership with Anglo-American forces, progressed.

[4][20][d] During their time in Brindisi d'Acquarone continued to maintain close contact on behalf of the king with the men who were emerging as the future political leaders of post-fascist Italy, such as Benedetto Croce, Enrico De Nicola, Giovanni Porzio, Giulio Rodinò and Carlo Sforza.

It was widely accepted that Pietro d'Acquarone continued to exercise a powerful influence on the decisions of the monarch, even taking it upon himself, on occasion, to oppose Marshal Badoglio.

[4][21] He was also strongly opposed to creating volunteer corps (the "Gruppi Combattenti Italia") under the leadership of Resistance General Giuseppe Pavone in Naples during September/October 1943, an initiative proposed by Benedetto Croce.

Larger forces were at play, but nevertheless a compromise proved possible, whereby on 10 April 1944 Victor Emmanuel agreed to hand over most of his powers and responsibilities to the Crown Prince, while Umberto took on what was termed the lieutenancy of the kingdom.