Rathbun, Brian C. “The Value and Values of Diplomacy.” In Diplomacy’s Value: Creating Security in 1920s Europe and the Contemporary Middle East, 2-10. Cornell University Press, 2014. http://www.jstor.org/stable/10.7591/j.ctt1287cbz.4.

These sources give the definition of diplomacy in a basic sense. Additionally, Rathbun gives a suggestion of the value of diplomacy as an international endeavor.

A 'new diplomacy' is being welcomed, and 'old diplomacy' is being pushed out.

Horne, John. “Reconstruction, Reform and Peace in Europe after the First World War.” In Revival After the Great War: Rebuild, Remember, Repair, Reform, edited by Luc Verpoest, Leen Engelen, Rajesh Heynickx, Jan Schmidt, Pieter Uyttenhove, and Pieter Verstraete, 297. Leuven University Press, 2020. https://doi.org/10.2307/j.ctv1b0fvbf.20.

Karns, Margaret P. and Karen A. Mingst. “International Organizations and Diplomacy.” The Oxford Handbook of Modern Diplomacy (2013): 124.

With the creation of organizations like the League of Nations, diplomacy has become multilateral, from a previously bilateral approach.

Siracusa, Joseph M. Diplomacy: A Very Short Introduction. Oxford: Oxford University Press, 2010.

The war can be attributed to long-established rivalries and alliances.

Vasquez, John A. “The Causes of the Second World War in Europe: A New Scientific Explanation.” International Political Science Review / Revue Internationale de Science Politique 17, no. 2 (1996): 165-166, http://www.jstor.org/stable/1601301.

Hitlers ambitions and transgressions begin the war. As Germany invades Poland, trends of territorial disputes in the beginning of wars - Macrohistory

Swistek, Göran. “The Nexus Between Public Diplomacy and Military Diplomacy in Foreign Affairs and Defense Policy.” Connections 11, no. 2 (2012): 82. http://www.jstor.org/stable/26326276.

Militarization as a form of diplomacy; pose as a threat or for defense purposes

The working-class population were especially hit, particularly in Belgium

Varying emotions on the War among certain nations (historical relativism)