Find out how World War I started and how America got involved. New weapons, such as poison gas, were used for the first time. These weapons made the war more terrible. Most soldiers lived and fought in trenches dug into the ground. What were those trenches like? What did they do for entertainment? What did it mean to go “over the top” into “No Man’s Land”? Each book in the 'American History Through Primary Sources' series delivers curriculum content by way of primary source material. Background knowledge of the subject matter is incorporated into the text. The books use clear, predictable text structures and have been leveled by a literacy expert to ensure accessibility. Vocabulary is defined at the point of use.