Operation Achse (German: Fall Achse, lit. 'Case Axis'), originally called Operation Alaric (Unternehmen Alarich), was the German operation to forcibly disarm the Italian armed forces after Italy's armistice with the Allies on 3 September 1943.
Several German divisions had entered Italy after the fall of Benito Mussolini in July 1943, while Italy was officially still an ally of Germany, despite the protests of the new Italian government under Pietro Badoglio. The armistice was made public on 8 September. German forces moved rapidly to take over the Italian zones of occupation in the Balkans and southern France, and to disarm Italian forces in Italy.
Some Italian troops, with no orders from superiors, and hampered by desertions, resisted the Germans. On the Greek island of Cephalonia, 1,315 Italian soldiers were killed in action against the Germans and over 5,100 Italian soldiers from the 33rd Infantry Division "Acqui" were summarily executed by the German Army after running out of ammunition and surrendering. In Rome, with the royal family and the government having fled, a disorganized defense by Italian troops of the capital was unable to withstand a German attack. Some individual soldiers and sometimes whole units, like the 24th Infantry Division "Pinerolo" in Thessaly, went over to the local resistance. Only in Sardinia, Corsica, Calabria and the southern part of Apulia were Italian troops able to offer successful resistance and hold off the Germans until relieved by the arrival of the Allies.
German plan
The first German combat units were sent to Italy to bolster its defenses against a probable Allied attack on Italian soil. Germany and Italy were still allies. The decision to create German units in Italy was made during the final phase of the Tunisian campaign; on 9 May 1943, two days after the fall of Tunis to the Allies, the German High Command (OKW) informed the Italian Supreme Command (Comando Supremo) that three new German units would be formed, mostly employing second-line German units evacuated from North Africa. They would be the Sardinia Command (later 90th Light Infantry Division), the Sicily Command (later 15th Infantry Division), and a "ready reserve". Adolf Hitler wrote to a dubious Benito Mussolini that since they were weak units that needed reinforcements, two additional German divisions would be sent from France. The 1st Fallschirm-Panzer Division Hermann Göring arrived mid-May 1943 and was sent to Sicily, and the 16th Panzer Division arrived in early June and was sent west of Bari. On 19 May also, the headquarters of general Hans Hube's XIV Panzer Corps was also sent from France to strengthen the command structure of the Commander-in-Chief South (Oberbefehlshaber Süd), Field Marshal Albert Kesselring.
On 20 May 1943, during a prolonged discussion at his headquarters, Hitler expressed his doubts about the political stability of the Fascist government and the danger of a collapse of his Italian ally. A report by the German diplomat Konstantin von Neurath found declining morale among the Italian population and pro-British sentiment spreading through the professional classes and the military. Hitler was convinced that the situation in the Mediterranean needed great attention, and a detailed plan had to be prepared for a collapse of Italy or an overthrow of Mussolini. More reports about a speech delivered by the Italian diplomat Giuseppe Bastianini, information from Heinrich Himmler's men in Italy and the presence in Sicily of General Mario Roatta, who was considered untrustworthy, strengthened Hitler's suspicions.
On 21 May, Field Marshal Wilhelm Keitel, the head of the OKW, issued guidelines developed to respond to the possible defection of Italy from the Axis. The plan envisioned a series of operations in different theaters: Operation Alarich, the invasion of the Italian mainland;
Operation Konstantin, the neutralization of the Italian forces in the Balkans;
Operation Siegfried, occupation of the Italian-occupied areas in Southern France;
Operation Nürnberg, to guard the France–Spain border;
Operation Kopenhagen, to control the passes on the France–Italy border.
Meanwhile, German reserves kept being redeployed to face potential threats in the Mediterranean theater. Hitler, seriously worried about the Balkans and in conflict with the Italian leadership and Mussolini himself because of collaboration agreements between the Italian and local partisan forces, decided to send the 1st Panzer Division to the Peloponnese and even considered sending to Italy his three elite Waffen-SS armored divisions, then deployed on the Eastern Front for Operation Citadel.
On 17 June Mussolini, after a partial refusal, urgently asked for two German armoured divisions, as a reinforcement to confront the powerful Allied forces. After more arguments caused by another change of mind by Mussolini and by a proposal by General Vittorio Ambrosio, the Chief of Staff of the Italian armed forces, to turn down German reinforcements and to move to Italy the Italian troops deployed in France and the Balkans, the ever-deteriorating situation (during Operation Corkscrew, Pantelleria surrendered without resistance on 11 June) induced Hitler to send three more German divisions: the 3rd Panzergrenadier Division, the 29th Panzergrenadier Division (both newly reconstituted in France after their decimation at Stalingrad), and the 26th Panzer Division. The last of them was deployed at Salerno on 9 July.
The 29th Panzergrenadier Division was sent to Foggia in mid-June and the 3rd Panzergrenadier Division was deployed north of Rome in the first days of July. Meanwhile, on 24 June, the Reichsführer-SS Brigade had been moved to Corsica, and in mid-July, the command of the 76th Panzerkorps (General Traugott Herr) also arrived.
Transfer of German forces to Italy
From the invasion of Sicily to the fall of Fascism
The Allied invasion of Sicily began on 10 July 1943, and established solid beachheads, despite Italian and German counterattacks. The political and military leaders of the two countries reacted immediately to the worsening situation. In Rome, Ambrosio urged unrealistic demands for help from Germany on Mussolini. Among the German commanders in Italy, Eberhard von Mackensen and Albert Kesselring became increasingly skeptical about Italian defense capabilities, and asked for reinforcements.
Hitler, more and more worried about an Italian collapse, decided to send the 1st Fallschirmjäger-Division to Sicily immediately, and then sent the headquarters of XIV Panzer Corps (General Hans Hube) and the 29th Panzergrenadier Division, ready for deployment, to Reggio Calabria. On 17 July, Hitler decided to meet with Mussolini and his collaborators, and assess their resolve to continue the war.
The meeting was near Feltre on 19 July 1943. On the same day, Rome was attacked by 690 bombers of the USAAF, which accelerated maneuvers by monarchists, high military officers, and even part of the Fascist leadership, more and more concerned with finding a way out of the war. The Feltre meeting accomplished little. Despite pleas by Ambrosio to present Italy's critical situation clearly and to ask for freedom of action to withdraw from the war, Mussolini was weak and indecisive and only asked for more German help in the defense of Italy, while Hitler made an exhausting speech in favor of fighting till the end. Moreover, Hitler gave an optimistic view of the situation and refused the sweeping Italian requests for more land and air support, mentioning technical and operative difficulties. But also, he did not heed the vehement requests of Jodl, Keitel and Warlimont: to create a unified command in Italy under German control, to move the many Italian troops in northern Italy south (towards the regions attacked by the Allies), and to give command of the Axis forces in the theatre to General Wolfram von Richthofen.
After the meeting, Hitler was convinced that he had lifted Mussolini's morale. Field Marshal Erwin Rommel had been put in charge of forces being organized in Bavaria for intervention in case of Italy's defection ("Operation Alaric"). Rommel was worried about the fate of German troops in Sicily and southern Italy, who would be cut off from Germany by an Italian "betrayal". But Hitler ignored warnings from Rommel. On 21 July, Hitler decided to suspend the planning of "Alaric" and to send German reinforcements to Italy. The codename "Alaric" was later quietly changed to "Achse" to avoid offending the Italians (Alaric was the Visigothic king who sacked Rome in 410).
On 25 July, before he learned of the fall of Mussolini, Hitler sent six Heer (Army) divisions to Italy, including a Panzer division, and three Waffen-SS divisions. Rommel and his headquarters (then in Munich) were sent to Thessaloniki to control a new army group in the Balkans.
German countermeasures after 25 July
Hitler and the German leadership were thus taken by surprise by the fall of Mussolini on 25 July; due to wrong information from the ambassador Hans Georg von Mackensen and by the military attaché Enno von Rintelen, who did not foresee that the meeting of the Grand Council of Fascism would threaten the Fascist regime, and instead thought that Mussolini would be able to strengthen collaboration with Nazi Germany. The news of the fall of Mussolini and the creation of a military government led by Marshal Pietro Badoglio surprised and enraged Hitler, who immediately understood that, despite assurances by Badoglio and Italian diplomats, the change of regime was a prelude to an Italian defection, which would endanger the German forces fighting in Southern Italy and the entire Wehrmacht presence in Southern Europe.
At first Hitler thought about intervening immediately with the forces already on site to occupy Rome and arrest Badoglio, the king and the members of the new government; however he soon changed his mind and, together with Jodl and Rommel (who had been urgently recalled from Greece) he decided to re-activate the planning of Operation "Alarich", to create a detailed plan to react to the Italian defection and swiftly occupy the Italian Peninsula, after sending enough reinforcements. Kesselring was told to be ready to change sides and to prepare the withdrawal of his forces from Sicily, Sardinia and Southern Italy; new directives were issued, with new operational plans.
In a matter of few days, the "Siegfried", "Konstantin", and "Kopenhagen" plans (ready since May) were confirmed, and new operations were studied: "Schwartz" to capture the Italian government in Rome, "Achse" to capture the Italian fleet, "Eiche" to free Mussolini from captivity, and "Student" to capture Rome. On 28 July, Hitler reviewed the operational planning: the "Konstantin" and "Alarich" plans were combined into a single plan for the occupation of Italy and the Balkans, which was called "Achse". On 5 August, on the advice of Admiral Ruge and because of the strengthening of the Italian defenses of Rome, the "Schwartz" plan was abandoned. Another problem for Hitler and the German leadership came from a lack of detailed information about Mussolini's fate and the refusal of Victor Emmanuel III to meet Hitler, which would have been an occasion for a sudden attack on the new Italian leadership.
While the planning was under way, the Wehrmacht command had begun the transfer of the divisions needed to enact operations when the Italians defected. Starting on 27 July, the 2. Fallschirmjäger-Division of General Hermann-Bernhard Ramcke was moved by air from Southern France to the Pratica di Mare Air Base, a move that surprised both the Italian commands and Kesselring, as neither had been warned beforehand. Meanwhile, on 31 July, General Kurt Student (commander of the 11th Airborne Corps, and due to take command of Ramcke's paratroopers) and SS-Hauptsturmführer Otto Skorzeny reached Kesselring in Frascati and outlined the "Schwarz" plan for him. This was however soon cancelled by Hitler.
Meanwhile, at 12:00 on 26 July Rommel had returned from Thessaloniki to Rastenburg, leaving command of the new Army Group F to Field Marshal von Weichs, and on 29 July he assumed command in Munich of a fake command, denominated Auffrischungsstab München, to hide the creation of a new army group which on 14 August would be moved to Bologna under the name of Army Group B, and would enact Operation "Achse" in Northern Italy.
At 02:15 on 26 July the 215th Infantry Division was the first German unit to enter Italy, heading for Liguria, while the Panzergrenadier Division Feldherrnhalle and the 715th Infantry Division were deployed to protect the passage through the alpine passes on the French–Italian border. The Italian commands protested and tried to stop the inflow of the divisions with some pretexts, but Kesselring intervened through the Italian Supreme Command on 1 August, and the 305th Infantry Division marched on foot first to Genoa and then to La Spezia. Meanwhile, more German units entered Italy: the 76th Infantry Division, on 2 August, heading for Savona; the 94th Infantry Division, on 4 August, heading for Susa and then Alessandria; the 87th Corps headquarters (General Gustav-Adolf von Zangen), which on 11 August established itself in Acqui and assumed command of the three newly-arrived German divisions.