I’ll start with some background then get into your specific questions.

Dr. Magnus Hirschfield was a German physician and sexologist between 1892 and his death in 1935. He was an outspoken advocate for “sexual minorities,” and was a gay man himself. Hirschfield spent time early in his career in the United States, where he noted similarities in gay culture to that of his home country, leading to his theory about the universality of homosexuality across the world. He would go on to continue his study of homosexuality and publish his findings.

Hirschfield treated many gay patients and was struck by their poor mental health and how often his patients attempted suicide; some successful, some not. This is around the same time Oscar Wilde was on trial, which really impacted Hirschfield as well. Hirschfield was the first person to produce evidence that homosexual individuals were more likely to commit or attempt suicide than their heterosexual counterparts.

In 1897 Hirschfield and a few colleagues formed the Scientific Humanitarian Committee with the motto “Justice Through Science.” The Committee continued and expanded on research of sexual minorities with the goal of eliminating social hostility toward LGBTQ+ individuals (although that acronym was not used) and with the hope of repealing Paragraph 175 of the German penal code which criminalized homosexuality.

Enter Karl M Baer

Karl M. Baer was born in 1885 in Germany. At birth, nurses noticed the baby’s “weird physical attributes.” Namely, the baby was intersex, possessing physical attributes of both male and female sex organs. The nurses assigned the baby “female” at birth. Growing up Baer knew they (using open pronouns because I don’t feel comfortable using female pronouns in this instance) were different and later in life, Baer would acknowledge they always felt like they were in the wrong body. In 1904, Baer started living as a male full time and using male pronouns. Baer was subsequently in an accident and taken to the hospital where he admitted to doctors he was in a bad mental state. Doctors also noticed his “unusual anatomy.” Hirschfield was called in to consult, and had previously done research on what he called “the third gender,” or intersex/transgender individuals. Hirschfield quickly realized what the problem was (this man has female anatomy) and suggested an operation to help, which happened in 1906. This is the first known case, however we don’t know exactly what kind of operation he underwent. During Nazi rule they burned most of Hirschfield’s records, including Baer’s.

It is likely that early gender-affirming surgeries consisted of hysterectomy or possibly mastectomy, but we just don’t know what it entailed for Baer.

What some consider the “birthing era of GAS” (gender-affirming surgery) began in earnest in 1919 after Hirschfield opened Institut für Sexualwissenschaft, or the Institute of Sexual Research. The institute housed Hirschfield’s archives, a library on sexuality, and provided education and medical services and consultations to homosexual individuals. The institute became sort of a haven for transgender individuals who were able to escape abuse, receive care, and even sometimes receive jobs within the institute. Surgeons at the institute performed the first vaginal constructions in the 1930s. One of the first patients was an institute employee known to us as only “Dorchen.” Another patient was Danish painter Lili Elbe whose story some may recognize from the movie “The Danish Girl.”

Around this same time, Dr. Harold Gillies was in the UK refining his techniques for genital construction. Gillies is considered the father of plastic surgery today. After WWI he found himself presented with a lot of patients who had sustained genital injuries during the war, and he sought to help them. This knowledge culminated in Gillies performing the first known phalloplasty in the 1940s when Gillies operated on fellow physician Dr. Michael Dillon.

As I mentioned briefly, the Nazis did not like Hirschfield’s institute - or him. Hirschfield was a gay Jewish man. Hirschfield eventually ended up in exile, Nazis closed down the institute, and most of the records were destroyed. That’s not the end of the tale though - his work lived beyond the paper it was written on.

Happy to get into modern era and the U.S. in a bit - I’ll come back and reply to this comment with the other information when I have time.