  This is a historical review of "Prandtl and the G\"ottingen School" from his
first work in 1898 to after WWII. We report the development of the boundary
layer theory and the investigations that lead Ludwig Prandtl in the spring of
1945 to use a energy cascade model to derive for fully developed turbulence the
Kolmogrov length scale. Working at the end of WWII he was not aware of the work
by Kolmogorov. Thus Ludwig Prandtl was before Onsager, von Weiz\"acker, and
Heisenberg in rederiving parts of K41 theory. In our historical analysis we
rely heavily on exchanges between Ludwig Prandtl with Theodore von K\'arm\'an
and Goeffrey Ingram Taylor and on the original notes by Ludwig Prandtl and
others.
