When Mott returned to Bristol after the war, (during that period, he worked on the role of plastic deformation on the progression of fracture cracks), his having met and hired of Frederick Charles Frank led both of them to develop, with the help of others such as Frank Nabarro and Alan Cottrell, to attack with the field of dislocations, in which Bristol shone with a new vigor, especially at the end of the 1940s. If Mott only produced early and somewhat minor contributions to that field, notably on alloy hardening with Nabarro and on the topology of a dislocation network lowering the apparent elastic constants of a crystal, there is no doubt that Mott's enthusiasm played its role in the three major steps forward in the field by F. C. Frank on crystal growth and plasticity and later, in Cambridge, by P. Hirsch on the thin film electron microscopy.