Who is Siegfried Sassoon from The Eye in the Door and what is their importance?

Siegfried Sassoon lived from 1886 to 1967. Sassoon was a renowned English poet whose anti-war writings distinguished him as one of the most important pacifist voices of the WWI era. Sassoon was also a homosexual and a combat veteran who experienced first-hand the trauma of the Front. Siegfried was an actual patient of William Rivers' at Craiglockhart War Hospital in Edinburgh, Scotland.