The 'Battle of Kos' was fought between German and Allied forces for the island of Kos in the Italian-held Dodecanese islands group of the Aegean Sea (3/4 October 1943).

The battle was precipitated by the armistice of September 1943 between the Allies and Italy, after which the British landed troops on Kos in 'Beneath' and thereby triggered the German 'Polarbär' to seize the island. Supported by major air power, the Germans quickly overwhelmed the Italian garrison and the recent British reinforcements, denying the Allies a base from which to attack the German presence in the Balkans and leading to the expulsion and death of the island’s Jewish population.

With the capitulation of Italy in September 1943, German forces in the Balkans and the Mediterranean moved to seize Italian-held areas. At the same time, the Allies, under the instigation of Winston Churchill, the British prime minister, endeavoured to occupy the Dodecanese islands group. These islands, under Italian control since 1912, were strategically located in the south-eastern part of the Aegean Sea, and Churchill hoped to use them as a base against German positions in the Balkans, and as a means to pressure neutral Turkey into the war on the Allied side.

With an area of 114 sq miles (295.3 km²), Kos is the third largest of the Dodecanese islands, and has a length of 25 miles 40 km) and maximum width of 5 miles (8 km). The coast is 70 miles (112 m) long, and has several substantial promontories.

The main prize of the Aegean Sea, the island of Rhodes, fell to a swift attack by a German mechanised brigade. Nevertheless, British forces landed on several islands, most notably Kos and Léros, and together with the Italian forces located there, there were hopes of eventually regaining Rhodes. On 13 September 1943 a force of 38 Consolidated Liberator four-engined heavy bombers from North Africa bombed the three airfields on Rhodes, effectively grounding the Luftwaffe contingent on the island, while Special Boat Section units landed on Kos, occupying the port and the airfield near the village of Antimachia. On 14 September two Bristol Beaufighter twin-engined heavy fighters and a number of Supermarine Spitfire single-engined fighters of the South African Air Force’s No. 7 Squadron arrived on the airfield. On the night of 14/15 September, 120 paratroopers of the 11/Parachute Regiment were dropped onto the island by Douglas Dakota twin-engined transport aircraft of the RAF’s No. 216 Squadron. The paratroopers were welcomed by the Italian garrison, who laid straw on the landing zone.

At first light on 15 September, a standing patrol of two Spitfire fighters of No. 7 Squadron was maintained over Kos to give cover to the transport aircraft and ships bringing stores and reinforcements. Among these were the first troops of the RAF Regiment who flew from the British mandated territory of Palestine with nine Hispano-Suiza HS.404 cannon for anti-aircraft defence, followed two days later by a second detachment, which brought up to strength one of the first of the regiment’s squadrons to be transported to the battlefield by air with all its weapons.

On the ground, the Allied force consisted of the 1/Durham Light Infantry, one company of 11/Parachute of Major General F. A. M. Browning’s 1^st Airborne Division, one company of the SBS, and Royal Air Force (RAF) personnel all under the local command of Lieutenant Colonel L. R. F. Kenyon. The force totalled ca. 1,600 British men, although only 1,115 were combatants (880 army and 235 RAF Regiment) and about 3,500 Italian servicemen from the original garrison.

The German attack began on 17 September with a heavy air-bombardment. The Messerschmitt Bf 109 single-engined fighters and Junkers Ju 88 twin-engined medium bombers involved met at first with varying success, because of the RAF gunners on the ground and the Spitfire fighters in the air. However, 'butterfly' anti-personnel bomblets rendered Antimachia temporarily unserviceable and damaged the Dakota transport aircraft, but the first detachments of the Durham Light Infantry were landed. One Dakota came down in the sea and its occupants were rescued but interned in Turkey.

German bombing and strafing attacks continued to harass the garrison over the next few days. The Luftwaffe flew 100 aircraft into the Aegean Sea area, bringing their strength up to 360 aircraft. While the German air cover improved, the Allies could rely only on a limited number of aircraft as a result of the decision of General Wright D. Eisenhower concerning the provision of no support for the British involvement in the Balkan theatre: while the three British Middle East commanders-in-chief were responsible for the Aegean Sea operation, the disposition of forces was decided by Eisenhower, as the Middle East Command was part of the greater Mediterranean theatre. Eisenhower ruled that in no circumstances was the Dodecanese islands campaign to be allowed to influence, however slightly, the conduct of other campaigns in the Mediterranean. This meant that Middle East command could not look for permanent help from the Italian war theatre, but must be prepared to improvise when temporary naval and air forces could be spared. Eisenhower’s decision, in which he had the loyal backing of his deputy, Air Chief Marshal Sir Arthur Tedder, was a corollary of the beliefs of the US Chiefs-of-Staff that the Dodecanese islands operation typified British diversionary strategy which might well lead to some form of Balkan adventure.

The limited aircraft cover for the operation on Kos was completely inadequate and would have a serious effect on the British ability to defend the island. Over the weeks from 13 September to 3 October the Allied aircraft defending Kos suffered many losses from bombardment of the airfield and in air combat. By 26 September the No. 7 Squadron had been reduced to four serviceable aircraft, and the RAF’s No. 74 Squadron was flown on to Kos on this day.

The defenders' position on Kos, never enviable, became serious and then desperate, for the Italian anti-aircraft defence was negligible and their own resources meagre. To add to their troubles, the area round the airfield they had to protect was too rocky to permit digging in, and there was no time to build blast walls before the Germans were upon them. The air attacks were so severe that casualties inflicted on the British paratroopers forced them to be withdrawn on 25 September.

On 1 October, a concentration of shipping was observed in the ports of Crete, and early in the morning of the following day a convoy steaming to the north-north-east in the area to the south-east of Milos island was sighted by British aircraft. Urgent supplies were landed on Kos by five Dakota transports, and during their unloading the news came that a small German invasion fleet of 10 vessels was at sea. This flotilla carried a task force composed of a Kampfgruppe of the Crete-based 22^nd Division (Luftlande) commanded by Generalleutnant Friedrich-Wilhelm Müller, as well as special forces of Generalmajor Alexander von Pfuhlstein’s Division 'Brandenburg' from the Greek mainland: these special forces were one amphibious warfare battalion and one airborne battalion.

At 04.30 on 3 October the 'Polarbär' invasion of Kos began. By 12.00, some 1,200 Germans, well-armed and supported by light artillery and armoured cars, were ashore and in action. Dive-bombing by Junker 87 single-engined warplanes added to the difficulties of the defence, and in the afternoon Antimachia was overrun. The main German convoy, which had been attacked from the air, was estimated to have consisted of seven transport vessels, seven landing craft, three destroyers and numerous caique fishing craft and other small craft. The principal landings took place at Marmari and Tingachi in the northern central part of the island, and at Camare Bay in the south-west, with subsidiary landings at Forbici and Capo Foco on the north-eastern and south-eastern tips of the island.

Paratroopers were dropped to the west and south of Antimachia. By 12.00 the Germans were reported as having landed 1,500 men. At about 13.30 another small German airborne landing by one paratrooper company of the Division 'Brandenburg' was made in the centre of the island, and more troops arrived by sea. For the British forces the situation was reported as confused, but by 18.00 it was further reported as critical. The Durham Light Infantry, SBS and paratroopers fought gallantly, but in the face of superior numbers and heavier equipment were forced to withdraw to positions covering the town and port of Kos and the airfield. That evening the Germans attacked the British positions in strength, reducing the British position to a small area around the town of Kos. The German strength had been reinforced to an estimated 4,000 men by the evening of 3 October.

The Italian and British forces had ceased organised resistance by 06.00 on 4 October. 1,388 British and 3,145 Italians were taken prisoner, while the captured Italian commander of the island, Colonnello Felice Leggio, and nearly 100 of his officers were shot in a major war crime by the Germans. A German communiqué of 5 October reporting the cessation of hostilities on Kos gave the number of prisoners taken as 600 British and 2,500 Italian men, with more Italians still surrendering themselves. A number of the British force escaped to neighbouring islands and were rescued by the Special Boat Service operating at night.

The loss of Kos would have disastrous consequences for British operations in the Dodecanese islands group. Deprived of air cover, the Allies were in the long run unable to hold the other islands, while the Germans pressed their advantage, capturing Léros a month later and completing their conquest of the Dodecanese islands group by the end of November.

A further consequence of the German occupation of Kos was the deportation of the small but long-established Jewish community to European death camps, from which none ever returned.