I was lucky enough to read the complete Memoirs of George Sherston which gives Sassoon's biography from a youngster and shows background etc. The reader gets a fuller picture of Sassoon. One must bear in mind that Sassoon was a poet and that like Graves, may have occasionally indulged in a bit of poetic licence. Again, a classic and I would say a must read. With Capt. Dunn, Sassoon, Graves and Frank Richards, the Welsh Fusiliers were the best served regiment from a documentary point of view. Each book, deservedly seen as a classic.
In both instances I'd change "occasionally indulged in a bit of poetic licence"to sometimes quaffed great draughts of it. but neither of them pretended that these books were sober historical records but novels based on their experience and none the worse for that.
My current anorakic reading is "The naval blockade 1914 -18" translated from the French (published in the 1920s). Cuts through a lot of myths