Many know of St. Theresa Benedicta of the Cross (Edith Stein), but there are many other female saints who were martyrs during WWII.
Blessed Santia Szymkowiak was a member of the Congregation of the Daughters of Our Lady of Sorrows, also known as the Seraphic Sisters. The Nazis overran her convent in Poznan in Poland in 1939 and Santia was conscripted as translator for the Germans. She had a chance to escape, but chose instead to stay with her community, where she made her solemn vows on July 6, 1942. She would die the following month, having contracted tuberculosis in the prison camp. She wrote in her diary, "Jesus wants me to be a holy religious and He will not be happy with me until I use all my strength for Him and become a saint...I have to become a saint at all costs. This is my constant preoccupation." Santia was beatified in 2002.
Further to the east and north in Nowogrodek, the Sisters of the Holy Family of Nazareth were placed under arrest by the Gestapo. These eleven nuns had prayed for all the Jews in their town deported to death camps, as well as the 120 factory workers who had been sentenced to death, along with their chaplain. "My God," prayed Maria Stella Mardozewicz, the superior of the community, "if lives must be sacrificed, it is better that they should shoot us rather than those who have families. We pray that God may accept our offer." Her prayers were answered. Frustrated by the Polish sisters' holiness, the Gestapo guards led the nuns out to the woods on the morning of July 31, 1943. They were forced to kneel before an open grave and were summarily shot, one by one. These eleven sisters were beatified in 2000.
These are the true unknown heroes of the Second World War.