It is important to keep in mind that Vacheron & Constantin was acquired by the Jaeger-Lecoultre group in 1938. It only became independant again when Georges Ketterer bought the majority of the V&C shares in 1965.
At the time of the merger, there were 3 different companies in charge of the distribution of JLC or V&C in the U.S.
1. Jaeger Watch Co Inc, created in New York in 1926, where Lecoultre & Cie had a minority stake (25%). With a strong focus on aircraft and car instruments and clocks.
2. Le Coultre S.H. of America, created in 1936 to promote fine watches.
3. Vacheron & Constantin Watch Co, distribution arm of V&C in the U.S. that was very weak after the Great Crisis.
As the U.S. were considered as an under-penetrated market with high potential, the management of the newly-merged entity decided to solve their distribution issue by negotiating an agreement with the Wittnauer-Longines group in order to ensure an effective and strong promotion of both Le Coultre and V&C watches in the U.S. This distribution agreement was signed just before WW2.
In parallel, Le Coultre & Cie remained a strategic supplier for Jaeger Watch Co Inc, although the U.S.based company had started to develop its own capacities and increase the part of its local production due to the pressure of import taxes and a highly competitive auto market.
I have read that Georges Ketterer, that had been in charge of V&C global sales since 1938, was not really satisfied by this move and quickly suggested an independant organization for V&C so that this premium brand could be better distinguished. All the confusion about the Mystery watch is a good example that he was right!
(credit :
https://vintagewatchinc.com )