There's so much about St. Teresa Benedicta of the Cross (aka Edith Stein)! You can read a little bit about her here.
I found the following about her in Voices of the Saints by Bert Ghezzi:
Edith had been raised in a devout Jewish family, but abandoned her faith in her youth. As a student, however, Edith had discovered Catholicism. She became a convert in 1921 after reading Teresa of Avila's Autobiography.
In 1932 she was appointed lecturer at the Educational Institute in Muenster. But when the Nazis came to power a year later, she was fired because she was a Jew. Edith viewed her dismissal as an opportunity to act on a long-standing desire to become a nun, and she entered the Carmelite community at Cologne.
Realizing that the Nazis would eventually capture her, she wrote the following letter:
It is good to remember, these days, that poverty implies being ready to leave our home in our dear convent. We have bound ourselves to the enclosure, but God has not bound himself to protect me in the enclosure-walls forever. He does not need to, because he has other walls with which to protect us.
The situation is parallel to the use of the sacraments; for these are the preordained means of grace, and we can scarcely be too eager to receive them. But God is not restricted by them. At the moment in which we are cut off from the sacraments by external power, he can more than compensate us in some other way; and he will do so the more surely, the more faithfully we have gone to the sacraments beforehand.
Similarly it is our solemn duty to observe the precepts of the enclosure as conscientiously as possible so as to live undisturbed, hidden with Christ in God. If we have done so faithfully, and if we are driven out onto the street, then our Lord will send his angels to encircle us, and their invisible wings will enfold us in a peace more secure than that of the highest and most solid convent walls. Certainly we ought to pray that we shall be spared the experience, but only with the deeply sincere addition: "Not mine, but thy will be done."
On August 2, 1942, the SS seized Edith and other Jews. She was executed at Auschwitz a week later.