  Superfluidity is a remarkable manifestation of quantum mechanics at the
macroscopic level. This article describes the history of its discovery, which
took place at a particularly difficult period of the twentieth century. A
special emphasis is given to the role of J.F. Allen, D. Misener, P. Kapitza, F.
London, L. Tisza and L.D. Landau. The nature and the importance of their
respective contributions are analyzed and compared. Of particular interest is
the controversy between Landau on one side, London and Tisza on the other,
concerning the relevance of Bose-Einstein condensation to the whole issue, and
also on the nature of thermal excitations in superfluid helium 4. In order to
aid my understanding of this period, I have collected several testimonies which
inform us about the work and attitude of these great scientists.
