'Herbstgewitter' (i) was a German two-part operation ('Herbstgewitter I' and 'Herbstgewitter II') against the partisan forces of Marshal Josip Broz Tito in the Dalmatian islands off the coast of German-occupied Yugoslavia (23 October/31 December 1943).

The undertaking was part of the Axis offensive known to the communist forces as the Sixth Enemy Offensive, which comprised three linked operations known to the Germans as 'Kugelblitz' (ii), 'Schneesturm' and 'Herbstgewitter' (i), and took the form of a series of major anti-partisan offensives planned by the German forces for a time late in 1943 and early in 1944 to strike a major blow against the partisan forces in the north-western area of Yugoslavia.

In 'Herbstgewitter I' of 23 October/11 November, the German forces swept the Peljesac peninsula in Croatia, and in 'Herbstgewitter II' of 22/36 December took the partisan forces' logistics base on Korčula island off the Dalmatian coast, which had proved an ideal staging point for Allied supplies being delivered by sea from Italy.

The forces involved were, on the German side, the 750^th Jägerregiment and 668^th Artillerieregiment of Generalleutnant Josef Kübler’s 118^th Jägerdivision, elements of the 800^th Küstenjägerabteilung of Generalmajor Alexander von Pfuhlstein’s Division 'Brandenburg', and one company of tanks; and, on the Yugoslav side, the 600-man 13^th 'Dalmatia' Brigade of the 26^th 'Dalmatia' Division, 300-man 1^st 'Overseas' Brigade, 250-man 'Korčula' Partisan Detachment and elements of the 1^st 'Dalmatia' Assault Brigade of the 9^th Division.

The operation began at a time just before dawn on 22 December as two German detachments departed by sea from ports on the Peljesac peninsula, and by evening these German forces had landed and severed the main road connecting the western and eastern parts of Korčula. The defence of Korčula at the beginning of the battle was founded on two partisan brigades and a detachment of local partisans, almost all of these units personnel being young and inexperienced, and the better battalions fell back from their initial positions along the coast and prepared for a counterattack. Under cover of fog, on 23 December the Germans delivered reinforcements to their units on the island, and with armoured support broke deep into the main partisan defences, causing a panic which soon led to a disorganised retreat. At the same time, in an observation post near Smokvica, both the commander of 26^th 'Dalmatia' Division, Nikola Martinović, and the local political commissar, who were jointly responsible for the defence of Korčula, were seriously wounded. In the evening a runner from the forces on the southern coast reported to Martinović that Germans were making another landing, this time at Karbuna, which meant that the partisan forces were now also being attacked from the rear.

In these circumstances it was soon decided that the remaining partisan forces and as many civilians as possible should abandon Korčula. All remaining partisan units were ordered to move for the defence of a beach-head around Vela Luka and Prigradice, from where several thousand refugees would be evacuated, initially to Hvar. There were some 40 vessels available for the evacuation, but panic decreased significantly eroded any chance of completing an effective withdrawal. The partisan brigades soon started to abandon their sectors in the beach-head’s defensive perimeter as men attempted to reach the vessels as soon as possible. Moreover, the captains of some vessels refused to sail to remoter coves to collect smaller units, and reached Hvar empty. These vessels were immediately sent back to Korcula under escort of an armed ship. Under cover of an Allied air umbrella, the evacuation continued during the following day and night, but large numbers of partisans and refugees still remained hidden on the island.

The Yugoslav assessment of this defeat revealed that some 1,150 troops had been lost, together with all of the artillery and almost all other matériel on the island. This was one of the worst defeats ever suffered by the partisan forces along the Dalmatian coast. More important than these immediate loss, however, were the reprisals inflicted on the partisan garrison. Generalfeldmarschall Maximilian Reichsfreiherr von Weichs, commanding Heeresgruppe 'F' in the Balkans and also the Oberbefehlshaber 'Südost', had received a report on the shooting of 29 Germans (three officers and 26 men) captured by the 29^th 'Dalmatia' Division near Mostar, and thus ordered the execution of 220 prisoners from Korčula in reprisal, giving the partisans additional ammunition for their propaganda campaign.

The 'Herbstgewitter III', 'Herbstgewitter IV', 'Herbstgewitter V' and 'Herbstgewitter VI' operations were planned as amphibious assaults on Mljet, Hvar, Brac and Solta, and Mljet was captured without resistance in 'Herbstgewitter III' on 30/31 December 1943. A revision of the German overall scheme for this area then led to changes to the last three, which were then allocated the new codenames 'Morgenwind II' for the 12 January landing on Solta, 'Morgenwind I' for the 13 January landing on Brac, and 'Walzertraum' (iii) for the 19 January landing on Hvar.