Cambridge University Library holds the world’s richest assemblage of Sassoon’s manuscripts and archival papers. Accumulated from various sources over the course of several decades, the collection was magnificently augmented in 2009 with the acquisition of the papers formerly retained in the possession of Sassoon’s only child, George. A gifted diarist, Sassoon kept a journal for most of his life, and the papers include a run stretching from 1905 to 1959. At the heart of this series are the war diaries, a fascinating resource for the study of the literature of the First World War which enables a fresh analysis of Sassoon’s experience of the catastrophic war which influenced him profoundly.
The journals are freely available online at http://cudl.lib.cam.ac.uk/collections/sassoon
The Cambridge Digital Library also has images of medieval manuscripts.