Corrie called her group "God's underground" (Chapter 7).
The Jews who were hiding in the Beje and the members of the Ten Boom family who were helping them were part of a larger underground network which had developed to protect Jews from Nazi atrocities. At the time that Corrie identified them by their informal name,
"eighty Dutchmen - elderly women and middle-aged men along with (the) teenagers - were working in God's underground...most of these people never saw one another...face-to-face contacts (were kept) as few as possible...but all knew the Beje...it was headquarters, the center of a spreading web...the knot where all threads crossed".
Holland had fallen to Germany in the spring of 1942. At first, the presence of Nazi troops had appeared to be relatively innocuous, but as time passed "each month the occupation seemed to grow harsher, restrictions more numerous". The "true horror...came over (the people) only slowly", beginning with minor exclusions and sporadic attacks on Jews. Before long, however, people began to disappear. Some had been "spirited away by the Gestapo", while others had gone into hiding before that could happen to them.
A year and a half after the invasion, Corrie had witnessed a group of German soldiers forcing their way into the home and shop of a Jewish neighbor. Although they did not harm the man at the time, it was evident that his life was in danger. The Ten Booms arranged for the neighbor and his wife to go to Amsterdam to stay with son Willem, and discovered that Willem and his own son Kik were actively involved in an active underground movement there. As the German threat intensified and more and more Jews feared for their lives, the Ten Booms became increasingly involved in the underground network in Haarlem, sheltering several exiles in the "hiding place" created in the labyrinthine upper level of the Beje (Chapters 5-7).