All three of these aircraft originated with a 1940 requirement for a large assault glider in preparation for
Operation Sealion, the projected invasion of Britain. Although Operation Sealion had effectively been cancelled by the time the requirement was issued in October 1940, there was still an urgent need for this sort of heavy air transport capability, as attention was now focused on Operation Barbarossa, the future invasion of the Soviet Union.

On 18 October 1940, Messerschmitt and Junkers were given 14 days to submit proposals for a large transport glider capable of lifting loads including an 88mm gun and its half-track tractor, or a Panzer IV medium tank.
Messerschmitt were ordered to base their design on a fabric-covered tubular steel air-frame, whereas Junkers, although renowned for their expertise with all-metal aircraft, were told that their glider had to be entirely wooden. Junkers technical staff protested that they had no knowledge of wooden aircraft construction and no skilled wood-workers, but were overruled.
The resulting Junkers 322 Mammut was a disaster – the first tank to be loaded crashed through the floor – and it was quickly abandoned.
Messerschmitt’s design was ordered into production as the Me321. The type’s worst fault was its sheer weight: fully loaded aircraft could only just be towed by three Bf110s and required rocket-assisted take-off (RATO) packs to get into the air. Although about 200 Me321s were completed before production ended in 1942, it was clear that something better was needed.
Strengths: exceptional carrying capacity
Drawbacks: required rocket-assisted launch; slow and vulnerable
Lifting capacity
The solution adopted was to develop a powered version of the Me321, designated the Me323. Both four- and six-engine versions were tested, but the four-engine prototype was quickly rejected, as it still had to be towed into the air. The six-engine version proved to be capable of taking off under its own power (although it still required RATO packs when fully loaded) and was accepted for service as the Me323D.

A total of 198 Me323s were completed before production ended in April 1944. They were very slow and vulnerable to Allied fighters, despite a heavy defensive armament of up to two 20mm MG151 cannon in wing turrets and seven 13mm MG131 machine-guns in the nose and fuselage.
On 22 April 1943, a formation of 27 fully loaded Me323s escorted by Bf109 fighters was intercepted near Sicily by seven squadrons of Spitfires and P-40s. Only six Gigants survived.
For all its problems, the type had a remarkable lifting capacity for its era and played a particularly important role in supplying Axis forces on the Russian front. Typical loads included 120 fully equipped troops, 60 stretcher cases with medical attendants, or 9,750kg of general stores.
After the war, it was believed no complete Me323 survived, although Berlin’s Air Force Museum of the German Federal Armed Forces held a main wing spar in its collection.
Then, in 2012, a ruined but intact Me323 was located eight nautical miles off the Maddalena islands off Sardinia, at a depth of 200ft, after a long search by a team of amateur historians.
The Me323 was on its way from a German base in Sardinia to the city of Pistoia in Tuscany
in July 1943 when, like so many of its counterparts, it was shot down by Allied aircraft. •
Image: Wikimedia Commons.