'Beneath' was a British operation to occupy the island of Kos in the Dodecanese islands group of the south-eastern Aegean Sea (13/15 September 1943).

With the capitulation of Italy in September 1943, German forces in the Balkans moved swiftly to take over the Italian-held occupation areas. At the same time, the Allies, largely at the instigation of Prime Minister Winston Churchill, attempted to occupy the Dodecanese islands group.

Under Italian control since the end of the Italo-Turkish War in 1912, these islands were strategically located in the south-eastern part of the Aegean Sea, and Churchill hoped to use them as a base area against German positions in the Balkans, especially the Romanian oilfields and associated refineries at Ploieşti, and as a means to persuade neutral Turkey to enter the war on the side of the Allies for a joint offensive into Thrace and Bulgaria.

The main prize was the island of Rhodes, but the British were forestalled in their planned 'Accolade' assault when this island fell to an attack, conceived and executed with great speed, by Generalleutnant Ulrich Kleemann’s Sturmdivision 'Rhodos'. Nevertheless, British forces landed on several islands, most notably Kos, Léros and Sámos. The British hoped that their forces, together with the Italian forces located there, might then be able to take Rhodes with other British forces operating from Cyprus and Palestine.

On 13 September 1943 a force of 38 Consolidated B-24 Liberator four-engined heavy bombers operating from North Africa bombed the three airfields on Rhodes, effectively grounding the German aircraft based on the island, while a Special Boat Squadron detachment under Major the Earl Jellicoe landed on Kos and was received by Colonnello Felice Leggio, the commandant, who informed Jellicoe that the Italians would surrender the island if the British landed reinforcements. The SBS party occupied 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 No. 7 Squadron, South African Air Force, landed on the airfield. On the night of the 14/15 September 120 men of the 11/Parachute Regiment were dropped by Douglas Dakota twin-engined transport aircraft of the RAF’s No. 216 Squadron. The paratroopers were welcomed by the Italian garrison.

At dawn 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 airfield defence troops of the RAF Regiment, who were flown from Palestine with nine 20-mm 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. On the ground, the Allied force comprised the 1/Durham Light Infantry, 120 men of A Company of the 11/Parachute, a number of SBS men, and RAF personnel under the command of Lieutenant Colonel L. R. F. Kenyon. The force totalled about 1,600 British personnel including 1,115 combatants (880 army and 235 RAF), as well as some 3,500 Italians from the original garrison.

The German riposte to 'Beneath' began on 17 September with the first of several heavy air bombardments. The Messerschmitt Bf 109 single-engined fighters and Junkers Ju 88 twin-engined medium bombers involved in this effort initially met with only varying success, for the RAF anti-aircraft gunners and the SAAF Spitfire fighters gave a good account of themselves. The German bombs rendered Antimachia airfield temporarily unserviceable, however, and also damaged Dakota transport aircraft, but the first detachments of the Durham Light Infantry were landed, although one Dakota came down in the sea and its occupants were rescued but interned in Turkey.

German bomber and fighter-bomber 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. But while the strength of the German local air capability improved, the Allies could rely on only a limited number of aircraft due to decisions made by General Dwight D. Eisenhower, the Allied supreme commander in the Mediterranean theatre, concerning support for the British involvement in the Balkan theatre, which he and most Americans saw as a British attempt to gain advantage for the post-war world but which had little or nothing to offer in the prosecution of the war. This meant that the British Middle East Command could not look for permanent help from the Italian theatre, but must be prepared to improvise when temporary naval and air forces could be spared. This decision by Eisenhower, in which he was backed by his deputy, Air Chief Marshal Sir Arthur Tedder, was a corollary of the beliefs of the US Chiefs-of-Staff that the Dodecanese operation typified British diversionary strategy which might well lead to some form of Balkan adventure.

The air cover for 'Beneath' was therefore woefully inadequate, as the British lacked the long-range fighters that could have provided cover for the islands and the maritime approaches to it, from bases in Cyprus, and inevitably this had a malign effect on the British ability to defend and thereby maintain their hold on the island. In the period from 13 September to 3 October the Allied aircraft defending Kos suffered numerous losses both to the German bombing of Antimachia airfield and two improved airstrips at Lambi and Tingachi, and to air combat. By 26 September No. 7 Squadron had been reduced to a mere four serviceable aircraft, but on this day the RAF’s No. 74 Squadron flew into Kos with eight Spitfire fighters.

The defenders' position on Kos had not been good even up to this time, but was now increasingly serious and rapidly became desperate, for the Italian anti-aircraft defence capability was negligible and the British resources meagre. To add to their troubles, the area round the airfield they had to protect was too rocky to permit troops to dig in, and there was no time to build blast walls to protect aircraft before German attacks fell on them. The air attacks were so severe that casualties inflicted on the British paratroopers forced their withdrawal on 25 September.

Meanwhile the Germans were planning and building up their strength for 'Polarbär' to retake the island.