Before the war started in the Netherlands, the Oversteegen family hid people from Lithuania in the hold of their ship.[3][why?]

[2] During World War II, the Oversteegen family hid a Jewish couple in their home.

[3] Freddie Oversteegen and her older sister Truus began handing out anti-Nazi pamphlets, which attracted the notice of Haarlem Council of Resistance commander Frans van der Wiel.

[3][4] Oversteegen, her sister, and friend Hannie Schaft worked to sabotage the Nazi military presence in the Netherlands.

[2][5] Oversteegen served as a board member on the National Hannie Schaft Foundation, which was established by her sister, Truus.