Reinhold Baer was born in Berlin on July, 1902. He was awarded his Ph.D at the University of Göttingen in 1925 for a thesis in geometry. Between 1926 and 1928 he held an Assistantship in Freiburg, where through the influence of alfred Loewy he became interested in algebra; in 1928 he received his Habilitation from the University of Freiburg. In 1929 he married Marianne Kirstein. Thus Baer met Friedrich Levi, an hold friend of the Kirstein family, and between them flourished a sincere friendship and fruitful scientific collaboration until Levi's death in 1966. In 1933, when Germany fell under the yoke of Nazism, Reinhold and Marianne fled to England where (as in the United States) a committee of academics had been formed to assist German colleagues who had lost their posts for political ends. In 1935 Baer was invited by Hermann Weyl to come to Princeton (USA), where an "Institute of Advanced Study" had recently been founded; Princeton had become the capital of the Mathematical world at the time, with six very eminent professors: T.W. Alexander, A. Einstein, M. Morse, J. von Neumann, O. Veblen and H. Weyl. Having spent two years in this city, where he continued his study of infinite abelian groups, begun in Manchester, Baer held a position for a short period at North Carolina University.
Subsequently Reinhold and Marianne spent 18 years in Urbana (Illinois), where Baer carried out intence research and supervised twenty graduates for the Ph.D degree; among whom where P.F. Conrad, D.G. Higman, K.G. Wolfson. In 1956 Baer was invited to accept a Professorship in Frankfurt and decided with Marianne to return to Germany. In the years that followed he produced many prominent doctorate students; among these were H.Bender, B. Fisher, H. Heineken, C. Hering, O.H. Kegel, H. Lüneburg and G. Michler. Around him he created a vibrant group, a true community of mathematicians, that Reinhold and Marianne transformed into a social community that also became a kind of extended family.
His own academic life was a very active and productive one: numerous mathematicians visited Frankfurt and many were his visits to other research centers. His most frequent venue was the "Mathematisches Forschunginstitute" at Oberwolfach. He had taken very much to heart the development of this institute and for many years took an active part in the organization of the conferences on group theory and geometry that were regularly held there. Even after his retirement from academic life in 1967, he and Marianne would spend four or five weeks, usually in the spring, at the Institute of Oberwolfach.
Reinhold and Marianne moved to Zurich, where he continued his research, his editorial work for "Archiv des Mathematik" and remained a reference and encouragement source for many young mathematicians. His last visit to Oberwolfach was in May 1979, when he was already ill. He entered hospital in August and died in October 1979.
In a beautiful biography published in the "Bullettin of the London Mathematical Society", Karl Gruenberg recalls the joy that Reinhold Baer had in producing mathematics and the enthusiasm he transmitted to his students. His biography closes with the words: "Many of us will always remember Reinhold Baer as he was in Oberwolfach. A trim and fit figure, dressed in an open-neck white shirt, grey flannel trousers and tennis shoes. A happy smile on his face, Marianne at his side, and surronded by young people."