What is the main conflict in Code Talker: A Novel About the Navajo Marines of World War Two by Joseph Bruchac?

In this novel, a man is telling his grandchildren how he came to receive several medals for his service in World War II. The grandfather, Ned Begay, was born on Navajo land, but attended a boarding school in order to learn English. Throughout his childhood Ned was told by the white man that using his sacred language was wrong. However, when World War II broke out, Ned learned that the government was recruiting Navajo men to use their language as a code the enemy could not decipher. Ned quickly chose to join up and play his part. Code Talker is a novel that is based in true history about American heroes who are all too often overlooked.