#OTD in 1928.
The novel The Well of Loneliness by Radclyffe Hall
Publication, originally scheduled for late 1928, was brought forward when he discovered that another novel with a lesbian theme, Compton Mackenzie's Extraordinary Women, was to be published in September. The Well appeared on 27 July, in a black cover with a plain jacket.
https://en.wikipedia.org/wiki/The_Well_of_Loneliness
The Well of Loneliness at PG:
https://gutenberg.org/ebooks/73042