In November 1942, as part of an operation known as Case Anton, the German Army crossed the demarcation line and occupied the territory previously under direct Vichy rule. This was the catalyst for Bloch's decision to join the French Resistance sometime between late 1942 and March 1943. Bloch was careful not to join simply because of his ethnicity or the laws that were passed against it. As Burguière has pointed out, and Bloch would have known, taking such a position would effectively "indict all Jews who did not join". Burguière has pinpointed Bloch's motive for joining the Resistance in his characteristic refusal to mince his words or play half a role. Bloch had previously expressed the view that "there can be no salvation where there is not some sacrifice". He sent his family away and returned to Lyon to join the underground.