"SI KLEGG Book 3" is a continuation of the adventures of Si Klegg, a young Union soldier from Indiana during the American Civil War, written by John McElroy. In this volume, Si Klegg and his comrade Shorty experience the brutal and grueling reality of war as they participate in battles such as Stones River, Chickamauga, and Missionary Ridge. They also face challenges such as illness, injury, and homesickness, and they must navigate the complex social dynamics of the army, including dealing with incompetent officers and confrontations with Confederate soldiers and civilians. The book also provides insights into the daily life of soldiers during the Civil War, including details about their clothing, food, and living conditions, as well as their thoughts and feelings about the war and their experiences.