[1] During the Second World War she was a member of the anti-Nazi Dutch Resistance,[2][3] together with her sister, Freddie Oversteegen,[4] and Hannie Schaft.

[5] Schaft and Truus Oversteegen were planning to liquidate policeman and NSB member Fake Krist on 25 October 1944, but other Haarlem Resistance fighters killed him first.

On 1 March 1945, NSB police officer Willem Zirkzee was executed by Schaft and Truus Oversteegen near the Krelagehuis on the Leidsevaart in Haarlem.

He survived the attack and, in 1948, testified in Amsterdam on behalf of his Velser girlfriend, the traitor Nelly Willy van der Meijden.

On 15 April 2014, Truus Menger-Oversteegen received the Mobilization War Cross with her sister from Prime Minister Mark Rutte.