In 1919 the writer was appointed by the Master and Fellows of Trinity College, Cambridge, Lees Knowles Lecturer in Military and Naval History for the academical year 1919-20, and the lectures are now printed almost exactly in the form in which they were delivered in November, 1919. The object of the Lecturer was to present in a convenient form the general conclusions about the administration of the Royal Navy from the Restoration to the Revolution arrived at in the introductory volume of his Catalogue of Pepysian Manuscripts, published by the Navy Records Society in 1903 with a dedication, in the two hundredth year after his death, 'to the memory of Samuel Pepys, a great public servant.' The evidence there collected shews that Pepys, familiar to the last generation in the sphere of literature, was also a leading figure in an entirely different world, who rendered inestimable services to naval administration in spite of the peculiar difficulties under which he worked. These conclusions, with a part of the evidence on which they depend, are summarised in the present volume.