Thanks to commenter emtgene, we have here the first true helicopter that was used in combat, the Folke-Achgelis Fa 223 Dragon
The Focke-Achgelis Fa 223 Drache (English: Dragon) was a helicopter developed by Germany during World War II. A single 750-kilowatt (1,010 hp) Bramo 323 radial engine powered two three-bladed 11.9-metre (39 ft) rotors mounted on twin booms on either side of the 12.2-metre (40 ft) long cylindrical fuselage. Although the Fa 223 is noted for being the first helicopter to attain production status, production of the helicopter was hampered by Allied bombing of the factory and only 20 were built.
The Fa 223 could cruise at 175 kilometres per hour (109 mph) with a top speed of 182 km/h (113 mph), and climb to an altitude of 7,100 m (23,300 ft). The Drache could transport cargo loads of over 1,000 kg (2,200 lb) at cruising speeds of 121 km/h (75 mph) and altitudes approaching 2,440 m (8,010 ft).
When Otto Skorzeny was planning his raid to abduct captured Italian dictator Benito Mussolini from the Albert Rifugio hotel on the Gran Sasso in September 1943, his original choice of aircraft was a Fa 223. The Fa 223 would be able to land directly in front of the hotel. However, the chosen aircraft broke down while en route, and Skorzeny instead was forced to use a Fieseler Fi-156.
In January 1945, the Air Ministry assigned the other three Drachen to Transportstaffel 40 (TS/40) at Mühldorf, Bavaria, the Luftwaffe's only operational helicopter squadron, equipped with at least five Flettner Fl 282s as well as the Drachen. TS/40 relocated to various sites before ending up at Ainring in Austria, where one of the Drachen was destroyed by its pilot to prevent it being captured and the other two were seized by US forces.
The US intended to ferry captured aircraft back to the USA aboard a ship, but only had room for one of the captured Drachen. The RAF objected to plans to destroy the other, the V14, so Gerstenhauer, with two observers, flew it across the English Channel from Cherbourg to RAF Beaulieu on 6 September 1945, the first crossing of the Channel by a helicopter. The V14 later made two test flights at RAF Beaulieu before being destroyed on 3 October, when a driveshaft failed. The accident was thought to be due to a failure to correctly tension the steel cables which secured the engine, despite warnings from Gerstenhauer.
Quite an interesting history.