The lesson provides a detailed overview of World War I, starting with the assassination of Archduke Franz Ferdinand by Gavrilo Princip, and highlighting key events such as the Schlieffen Plan and the entry of Britain and Italy into the war. It emphasizes the contributions of Commonwealth soldiers and volunteers, particularly women, who played significant roles both on the front lines and at home. The lesson also addresses Germany’s strategic errors, notably the naval attacks that led the United States to join the war, ultimately altering the course of history.