From Operation Mincemeat: How a Dead Man and a Bizarre Plan Fooled the Nazis and Assured an Allied Victory, by Ben Macintyre (Crown, 2010), Kindle pp. 291-293:
The most significant victim in the fallout on the Axis side was Mussolini himself. From the first Allied footfall in Sicily, Il Duce was doomed, though he refused to acknowledge it. Goebbels noted: “The only thing certain in this war is that Italy will lose it.” The Pact of Steel was cracking up. By July 18, the Allied front line had moved halfway up Sicily. That day, Mussolini sent an almost defiant cable to Hitler: “The sacrifice of my country cannot have as its principal purpose that of delaying a direct attack on Germany.” The Führer summoned him to an urgent meeting. Il Duce did not care to be summoned anywhere but went meekly. The two fascist leaders met in Feltre, fifty miles from Venice, where Hitler launched into a long harangue, lambasting the “inept and cowardly” Italian troops in Sicily and insisting: “What has happened now in Sicily must not be allowed to happen again.” In the midst of the tirade, an aide interrupted to inform Mussolini that Rome was under massive air attack, the first time the capital had been targeted. Mussolini sat impassively through the two-hour monologue. The great Italian bull seemed to be fatally gored, diminished, and distant. At the end of the excruciating meeting, he said simply: “We are fighting for a common cause, Führer.” It sounded more like an epitaph than a statement of solidarity. On July 22, Palermo fell to Patton’s American troops. Three days later, Mussolini was outvoted by the Fascist Grand Council, summoned by King Victor Emmanuel III to a private audience, and toppled. “It can’t go on any longer,” said the king: Mussolini must resign at once, to be replaced by Marshal Pietro Badoglio, the former chief of the armed forces. Italy’s deposed dictator left the royal Villa Savoia hidden in an ambulance, and the new government in Rome began the secret task of extracting Italy from the war and Hitler’s poisonous embrace. In Badoglio’s words: “Fascism fell, as was fitting, like a rotten pear.” The next day, Rommel was recalled from Greece to defend northern Italy.
Would it have fallen so fast, or rotted so quickly, without Operation Mincemeat? The invasion of Sicily was a far from perfect military operation, bedeviled by poor planning and personal rivalries between selfish and powerful men. A relatively small contingent of German troops successfully held up the advance of an Allied host seven times larger and then evacuated the island to continue the battle up mainland Italy. The fight for Sicily was grim, bitter, and costly. But how much worse would it have been had the Nazi high command been prepared for it? What if, say, the full-strength, battle-tempered First Panzer Division, instead of being dispatched to Greece to await an imaginary invasion, had been deployed along the coast at Gela?
It is impossible to calculate how many lives, on both sides of the conflict, were saved by Operation Mincemeat, or exactly how much it contributed to hastening the end of the war and the defeat of Hitler. The Allies had expected it would take ninety days to conquer Sicily. The occupation was completed on August 17, thirty-eight days after the invasion began. Looking back after the war, Professor Percy Ernst Schramm, keeper of the OKW war diary, left no doubt that the fake documents had played a critical role: “It is well known that under the influence of the letters, Hitler moved troops to Sardinia and southern Greece, thereby preventing them from taking part in the defence against [Husky].” In September, Italy formally surrendered, although the war in Italy would not end until May 1945.