US.24 Explain the reasons for American entry into World War I, including: the use of unrestricted submarine warfare, the Zimmerman Telegram, the defense of democracy, and economic motivations. US.25 Identify and explain the impact of the following on World War I (T.C.A. § 49-6-1006) • Harlem Hell Fighters US.23 Explain the causes of World War I and the reasons for the initial declaration of U.S. neutrality.