Every war requires more than just the efforts of traditional soldiers. Some heroes' stories are not appreciated during their time. In this book, you'll uncover the amazing tales of courageous and innovative people and groups who created-and cracked-seemingly unbreakable codes during times of war. In times of war, heroes are found both on and off the battlefield. In this series, readers will learn the stories of people from history who worked in secret, in danger, and on the home front. With resourcefulness, intelligence, and muscle, these fascinating people worked to support their countries and fellow citizens. Each 32-page book helps improve comprehension and builds confidence with guided post-reading questions and fun activities. Reading/teaching tips and a glossary are also included.