World War I was once called "the war to end all wars." It involved many countries around the world and marked the beginning of an increased American presence globally. World War I marked the start of trench warfare as countries carved up land all over Europe. More powerful and dependable firepower included improved machine guns and artillery. Navies fought using dreadnaughts, destroyers, and submarines, and airplanes were first used for warfare. The bloody battles of this war took place over four years setting the stage for World War II. Primary sources, full-color images, and maps depicting battle movements are sure to support reader comprehension.