'Most III' was a Polish clandestine operation by resistance forces to effect the transfer of captured and/or purloined German V-2 ballistic missile components from testing and manufacturing sites in occupied Poland for examination in the UK (25/26 July 1944).

From November 1943 onward, the intelligence division of the underground Armia Krajowa (home army) managed to obtain parts of the V-2 ballistic rocket, a new weapon which was being tested near Blizna in central Poland. The availability of parts increased from April 1944, when several test missiles fell near the village of Sarnaki, in the vicinity of the Bug river to the south of Siemiatycze.

Parts of the rocket were secured by the Armia Krajowa, and analysed at its secret laboratories in Warsaw by a team including Professor Janusz Groszkowski (radio and guidance), Marceli Struszyński (fuel), Bogdan Stefanowski (engine), Antoni Kocjan and others.

Known to the British as 'Wildhorn III', the 'Most III' undertaking was carried out on the night 25/26 July 1944. A Douglas Dakota transport aeroplane of No. 267 Squadron flew from Brindisi in southern Italy and landed at an Armia Krajowa outpost between the villages of Jadowniki Mokre and Wał-Ruda near Żabno, at the confluence of the Dunajec and Wisła rivers, to take on board about 110 lb (50 kg) of the most significant parts, as well as the scientists' final report, analyses, sketches and photographs.

This was the third time that a British aeroplane had landed in occupied Poland, hence the operation’s name.

The operation was undertaken with great caution as there was a substantial German presence in nearby villages. The aeroplane had problems in taking off as its landing gear had sunk into the marshy meadow. The crew could have abandoned and destroyed their machine, but with the help of the partisans the aeroplane managed to take off at the third attempt with the recovered V-2 components, and returned to Brindisi. In late July 1944, the parts were delivered to London.

On the outbound flight from Brindisi the aeroplane carried four Polish passengers, and on the return flight four different passengers. It had also been intended that Antoni Kocjan, who had studied parts of V-2 missiles, would be evacuated, but he had been arrested by the Gestapo and therefore was replaced by Jerzy Chmielewski.