Brandt was born Rut Hansen on Jan. 10, 1920, in Hamar, Norway. At age 16, she joined a socialist youth group, which remained active during Germany's World War II occupation of Norway; and in 1942, she fled with one of her sisters to neighboring Sweden.
In Stockholm, where she worked at the press office of the Norwegian Embassy, she met the exiled Willy Brandt.
Her first husband, Ole Olstadt Bergaust, died in 1946. The following year, she moved to the Norwegian military mission in Berlin, and in 1948 she married Willy Brandt, the AP reports.
Willy Brandt served as West Berlin's mayor for nine years until 1966, when he became foreign minister. Rut moved with him and their three sons to Bonn, where she headed the diplomatic spouses' association.
The Brandts separated in 1979, five years after Willy Brandt resigned as chancellor. They divorced in 1980, and Willy Brandt later married his longtime assistant, Brigitte Seebacher.