Quoting H. James Burgwyn’s Mussolini and the Salò Republic, 1943–1945: The Failure of a Puppet Regime, 275–278, 280:

As the RSI continued to unravel, Mussolini had to face an ominous and pending defeat at the hands of the Allies. Since military victory was beyond reach, he had only one option—a very slender one—to save both himself and the régime: diplomacy. Should he proceed alone or join forces with Hitler? Advising negotiations to the Führer, who deemed any approach to the despised Allies as shame and sacrilege, would be a tall order.

In February 1945 Mussolini mused on a plan for the Axis Powers to join the [Western] Allies in halting the spread of Communism. The Allied summit meeting in latter January at Yalta, which, in his view, had produced an abyss between the USA and USSR, provided him an opening. On the 28th he wrote Hitler that since he had an ace up his sleeve to play with Churchill, his bitter British antagonist could not refuse to parley: “My relations with Churchill are today such that difficulties a priori can be excluded.” He implored Hitler: “Let us delay no further! Führer! Let us not sacrifice our last chance!”¹⁶ He received no direct reply.

Churchill, reasoned the Duce, had recognized the danger to Europe of Stalin’s proposed take-over of Poland and the Baltic states. His entire country would be shaken by fear that the Soviet Union was poised to spread far afield in the Continent, and thus would finally be ready to seek help from the Axis Powers to check the Communist onslaught.¹⁷

Confident that he held the British prime minister in thrall, Mussolini, on 25 March 1945, revealed to Pavolini what he claimed to be powerful diplomatic leverage: “At the moment I hold that, to strengthen our hand, the most important thing is to put the correspondence and exchanges [I have] on accords with Churchill in a safe place. These documents will provide the inevitable proof of British bad faith. These documents are worth more to Italy than a war that has been won, because they will clarify to the world the true reasons for our intervention on the side of Germany.”¹⁸

Dumbfounded that the Western Powers were opening the door to Communist expansion in Europe, Mussolini described them as shortsighted and rigid. “One thing is certain: before the bar of History, the German and Italian allies can never be accused of responsibility for these errors.”¹⁹

For all the Duce’s bravado, there is not one iota of evidence to support his beliefs, as conclusively revealed by the Italian historian Mimmo Franzinelli. The supposed correspondence from Churchill consisted of one letter, dated 16 May 1940, encouraging Mussolini to stay out of the war. “Is it too late to stop a river of blood from flowing between the British and Italian peoples? We can no doubt inflict grievous injuries upon one another and maul each other cruelly and darken the Mediterranean with our strife. If you so decree, it must be so; but I declare that I have never been the enemy of Italian greatness nor ever at heart the foe of the Italian lawgiver.”

But this expression of good will was followed by a gentle reminder that England, even if alone, was prepared to go on to the end. “Hearken to it, I beseech you in all honor and respect, before the dread signal is given [for Italy to go to war against England]. It will never be given by us.”²⁰

Mussolini’s reply was not long in coming. In a note to the British prime minister a couple of days later, the Duce gruffly repeated his resentment over England’s sanctions against Italy during the Ethiopian War and the nature of his country’s “servitude” to Perfidious Albion in the Mediterranean. Italy would stand by the Axis partner no matter what.²¹ Churchill sent no further letter to the [Axis] dictator.²²

If Mussolini was eager to bring Hitler around to negotiations with the Allies, he was hesitant to undertake such a move on his own. “To act on an initiative by ourselves?” he wrote Clara Petacci on 14 March 1945. “This is not advisable. I don’t want to follow the footsteps of Savoy and the other traitors,”²³ he said with typical braggadocio.

Unable to move Hitler, the Duce had actually overcome such scruples before by searching for a deliberately “Italian” solution of the war. On 9 March he sent a priest to Switzerland with a peace proposal to the Vatican envoy, involving an alliance of Italy, Germany, and the [Western] Allies to defeat Soviet Communism.²⁴ Such bizarre overtures to the Allies revealed Mussolini’s vacillating between a “mad world of flames” and diplomatic mumbo jumbo.

Another fanciful proposal involved Mussolini’s son, Vittorio. Through him Mussolini transmitted a letter to Archbishop of Milan Cardinal Schuster, dated 13 March 1945, which proposed that Graziani’s soldiers, with Allied cooperation, suppress partisan bands, Communists, and strikes. The Allies would return the favor by disarming the partisans before the RSI units laid down their arms. There would be no criminal trials, no purges, and no action brought against those who had taken an oath to the RSI.

After peace had been restored, the Fascist Party would be dissolved and constitutional practices implemented. This fanciful proposal reached the Holy See, which informed Mussolini that the Allies did not intend to engage in negotiations outside unconditional surrender.²⁵

On 19 March 1945 Mussolini called Anfuso back to be undersecretary of state in the Foreign Ministry. Anfuso told the Duce that since [the Third Reich] was in its death throes, there was only slender hope that the British and Americans could be separated from the Russians. With the German-promised new weapons failing to show up quickly on the battlefield, Mussolini braced himself for the worst. In a hushed tone he uttered: “Sooner or later truth comes out. Fate marches inexorably on, nor is there any way of escaping it. Only a miracle can modify matters.”²⁶

Anfuso told Mussolini a week later that Ribbentrop had sought contacts with the Americans and British.²⁷ The Duce replied: “Up to a little time ago […] I believed that my mediation with Churchill might have been possible. Now, when one speaks of England to Hitler, he acts as if he has been bitten by a poisonous snake.”²⁸

In the hope of sparing Italy further ravages of war, Economics Minister Angelo Tarchi suggested on 29 March that he approach the Western Allies. The Duce gave him the go-ahead, saying: “You know that my initiatives, likewise supported by Hitler, for transforming the front have found only silence on the part of Churchill. In my proposals I placed no conditions either for myself or for the party. My purpose was once again only to save Europe from a Russian invasion, of concluding a war without having immediately created the necessity of making war yet again.”²⁹ (Such a statement was filled with misrepresentations, mainly that his “initiatives” were supported by Hitler.)

[…]

On 12 April, encouraged by the death of President Roosevelt, “that paraplegic weakling,” Mussolini perceived a ray of hope that the Allies would be prepared to consider a diplomatic solution of the war. If this should happen, he told Rahn on the 14th, the Yalta agreements would die and American appeasement of the Soviet Union would give way to fear of a Communist takeover of Europe.

Dismayed by notable Communist inroads in Greece, the [Western] Allies, fearing the same thing was happening in Italy, would seek support of the former Fascist enemy, which now loomed far less threatening than Stalin’s legions advancing deeply into Germany. Borghese and his X Mas would be offered weapons and reinforcements to hold off Tito’s advance in the Venezia Giulia.⁴²

In the far-fetched hope that the Allied armies in northern Italy were setting in motion a plan to contain Stalin’s juggernaut by a drive over the Alps into Germany, Mussolini would pitch in by bringing his resolutely anti-Communist régime into the Allied fold. Ergo: no Casablanca formula of “unconditional surrender” and no more threatening partisan movement permeated with pro-Soviet disciples.⁴³

(Emphasis added.)

As it turned out, Benito Mussolini’s hopes were not entirely irrational. See Operation Unthinkable and Operation GLADIO.