Gies (also known as Henk van Santen in The Diary of Anne Frank) was born and raised in Amsterdam's south side. He met his future wife, Miep Gies, in 1933 when he was a bookkeeper and she an office worker at a local textile company. It was not until after they'd gone their separate ways - Jan into the Dutch Social Services and Miep to Otto Frank's company, Opekta - that they met each other again socially in 1936. They married in Amsterdam on 16 July 1941, when Miep was threatened with deportation back to Vienna after she refused to join a Nazi women's group. Their wedding was attended by Otto and Anne Frank, Hermann van Pels and his wife Auguste van Pels, and Miep's colleagues Victor Kugler, Bep Voskuijl, and Johannes Kleiman. Later that year, Gies was appointed the nominal director of Otto Frank's company after Frank was forced to resign from the board under the newly introduced Nazi laws which forbade Jews to hold directorships, and from then on, the company traded under the name Gies & Co.