What was Niels Bohr's code name during the Manhattan Project?

Niels Bohr’s code name during the Manhattan Project was Nicholas Baker. The alias was used in the United States in 1943 and 1944, when Bohr joined Allied discussions about nuclear weapons and atomic research. Security officials needed to protect the identities of scientists connected with the wartime project, so Bohr traveled and communicated under a pseudonym.

Bohr had escaped Nazi-occupied Denmark in 1943 and reached Britain before traveling to the United States. He met senior figures involved in the Manhattan Project, including General Leslie Groves, and later visited Los Alamos. Although he was not one of the project’s principal bomb designers, his theoretical insight and advocacy for international openness influenced debates surrounding nuclear weapons.

The name is easy to confuse with “James Baker,” but that was the code name used by Bohr’s son Aage. “Nicholas Bohr” was not the alias. After the war, Bohr returned to Denmark and continued campaigning for international control and peaceful cooperation in nuclear science.