Junkers setbacks with crashes of prototypes in 1937 and 1938. Further refinements enabled certification in 1939 and spurred South African Airways to make an initial order for two aircraft fitted with US-built Pratt & Whitney engines. Just as the aircraft was being readied for its first commercial flights, World War II began. With the outbreak of hostilities, all models were requisitioned by the Luftwaffe for military air-transport roles, and later, long-range maritime patrol. Military aircraft production was begun by the company in the 1930s and eventually monopolized all its resources. Perhaps the most notable design was the Junkers Ju 87 "Stuka"
Junkers Bomber" design competition for a trans-Atlantic range strategic bomber saw the Junkers firm build two prototypes of its six-engined Junkers Ju 390, basically a stretch of the four-engined Ju 290 transport — competing against the trio of Me 264 four-engined prototypes as the only fully airworthy competitors for the contract, which had included designs from Focke-Wulf and Heinkel that were never built, with the competition ended in July 1944 due to the developing need for interceptors to defend the Reich. The Junkers company survived the Second World War and was reconstituted as Junkers GmbH and eventually merged into the MBB