I just read an excellent newer picture book,
The Cats of Krasinski Square by Karen Hesse. Hesse is most well known for her historical fiction novels, and her talent for making history come alive is evident in this picture book title as well. This story is based on a true event that happened in Warsaw during the Holocaust, when the Jewish Resistance fought back in many ways against the Nazis, in spite of terrible odds. This story tells about the cleverness of these resistance fighters in smuggling food and medicine to those imprisoned inside the Warsaw Ghetto walls...even when the Nazis came with dogs. It would be a great story for older children who are just beginning to learn about the Holocaust, as well short enough for a teacher to read with middle and high schoolers during class.
Read-alikes or read-beyonds: The Yellow Star: the legend of King Christian X of Denmark by Carmen Agra Deedy is another picture book about the resistance of the Danish people against the Nazis.
Number the Stars by Lois Lowry is an excellent chapter book novel about this topic, as well. We also have some great titles in the juvenile non-fiction, like
Resistance: Teen partisans and resisters who fought Nazi tyranny by Charles Anflick. You might also want to check out the movie,
Uprising, about the Warsaw Ghetto Uprising of 1943.