Maybe this is so old that it's dead, but I love me some Mormon history sources! Why didn't I find this sooner when it may have helped?

• Mangum, James I. "The Influence of the First World War on the Church of Jesus Christ of Latter-day Saints" (master's thesis, Brigham Young University, 2007)
• Kenneth L. Alford, “Joseph F. Smith and the First World War: Eventual Support and Latter-day Saint Chaplains,” in Joseph F. Smith: Reflections on the Man and His Times, ed. Craig K. Manscill, Brian D. Reeves, Guy L. Dorius, and J. B. Haws (Provo, UT: Religious Studies Center; Salt Lake City: Deseret Book, 2013), 434–55.
• Evans, Max J., ed. Utah Historical Quarterly: Utah and World War I 58:4 (Fall 1990)
• Richard E. Bennett, “‘How Long, Oh Lord, How Long?’ James E. Talmage and the Great War,” in Religious Educator 3, no. 1 (2002): 87–101.

General LDS Histories:

• Allen, James B., and Glen M. Leonard. The Story of the Latter-day Saints. 2d ed. Salt Lake City: Deseret Book, 1992
• Cowan, Richard O. The Latter-day Saint Century. Salt Lake City: Bookcraft, 1999. (earlier edition titled Mormonism in the Twentieth Century)
• Alexander, Thomas G., Mormonism in Transition: A History of the Latter-day Saints, 1890-1930. Urbana: University of Illinois Press, 1996 (2nd edition)
• Van Orden, Bruce A. Building Zion : The Latter-day Saints in Europe. Salt Lake City: Deseret Book, 1996
• Walker, Ronald W. "Sheaves, Bucklers, and the State: Mormon Leaders Respond to the Dilemmas of War," in The New Mormon History, ed. D. Michael Quinn (Salt Lake City: Signature Books, 1992)
• "Change and Consistency", Church History in the Fulness of Times. Salt Lake City: The Church of Jesus Christ of Latter-day Saints, 2003
• Brian Q. Cannon, “Chastisement of the Nations, 1914–45,” in Window of Faith: Latter-day Saint Perspectives on World History, ed. Roy A. Prete (Provo, UT: Religious Studies Center, Brigham Young University, 2005), 427–46.

Related Studies:

• Tate, George S. "'The Great World of the Spirits of the Dead'": Death, the Great War, and the 1918 Influenza Pandemic as Context for Doctrine and Covenants 138," BYU Studies 46:1 (2007): 5-40
• Bennett, Richard E. "'And I Saw the Hosts of the Dead, Both Small and Great': Joseph F. Smith, World War I, and His Visions of the Dead." Religious Educator 2:1 (2001): 105-125
• Anderson, Jeffery L. "Brothers across Enemy Lines: A Mission President and a German Soldier Correspond during World War I." BYU Studies 40:3 (2001):127-139.
• Jeffery L. Anderson, "Mormons and Germany, 1914-1933: A History of The Church of Jesus Christ of Latter-day Saints in Germany and Its Relationship with the German Governments from World War I to the Rise of Hitler" (master's thesis, Brigham Young University, 1991)
• Patricia Rushton, Lynn Clark Callister, Maile K. Wilson, "World War I," Latter-day Saint Nurses at War: A Story of Caring and Sacrifice (Provo, Utah: Religious Studies Center, Brigham Young University, 2005) 9–12.
• Wood, Robert S. and Taylor, Stan A. "J. Reuben Clark, Jr., and the American Approach to Foreign Policy," BYU Studies 13 (Spring 1973): 441-52
• Jorgensen, Lynne Watkins. "Begging to Be in the Battle: A Mormon Boy in World War I," Journal of Mormon History 29:2 (Spring 2003): 101-34
• Braby, Carol F. "Hannah S. Jenkins: Missionary Wife in Palestine, 1911-20," Journal of Mormon History 34:2 (Spring 2008): 43-72
• Karamesines, Patricia Gunter. "The Burn of the Brand," Irreantum 7:1 (2005): 153-55
• Black, Marcia and Robert S. McPherson, "Soldiers, Savers, Slackers, and Spies: Southeastern Utah's Response to World War I," Utah Historical Quarterly 63:1 (Winter 1995): 4-23