Johtje and Aart Vos didn't sit down one day and decide to begin rescuing Jews from the Nazis in their Dutch village of Laren. Their rescue work began with a piano, a child, and a suitcase.
When their good freinds, professional musicians Nap and Alice de Klijn, were ordered to move into the Jewish quarter in Amsterdam, the de Klijn's signed over ownership of one of their pianos to Johtje to protect if from the Germans. The de Klijn's also had a child who was hiding with another family, and when that hiding place suddenly became unsafe, Johtje and Aart took the child into their home, no questions asked. And when another good friend received word that he was also being forced to move to the Jewish section of Amsterdam, he asked the Voses if they would hide a suitcase of valuables for him. They agreed.
Before long the Voses had joined a Resistance organization composed of other like-minded people in the Laren area. The members of the Laren Resistance called themselves the Group. The Voses agreed to work for the Group by using their home as a hiding place for anyone on the run from the Nazis.
Opening paragraphs of "Johtje Vos: A Group Effort" from Women Heroes of World War II: 26 Stories of Espionage, Sabotage, Resistance, and Rescue.