Garnett had known some of the members of Bloomsbury before World War I, but none of them intimately. When the war began he joined a Quaker relief organization and spent some months in France. He returned to England a pacifist. He declared himself a conscientious objector and was allowed to choose alternative service as a farm laborer, working with Duncan Grant, the two of them living with Vanessa Bell. By the end of the war he was a member of what by then had become, self-consciously, the Bloomsbury Group.
The Golden Echo (1953), Garnett's memoirs, published after most of the members of Bloomsbury had died, is as good a portrait of the group as we have, although its three volumes were published before the age of absolute frankness about sexual matters. The reader of The Golden Echo learns a good deal about the friendships that held the group together, and it may be that Garnett's reticence is less distorting than the emphases supplied by the succeeding candor.
In 1921, Garnett married Ray Marshall, an artist who later illustrated his novel Lady into Fox. There were two sons by this marriage.