Let me start by saying, communication is so important not only in international relations but also in everyday life. World War I, World War II, and the Cold War all needed effective and timely communication to reach the end of the war.
Prior to WWI, Russian and German leaders communicated using telegrams and communicated well as these two leaders were cousins. Since these two leaders were able to communicate so quickly, Russia was able to mobilize its troops and prepare for what would be known as World War I. This communication was also effective in sounding the alarm of Austrian forces to gain a better foothold in the conflict.
The book then moves to The League of Nations. “The League of Nations was the first international institution to embody the collective security approach to the use of military power. The Covenant of the League spelled out the various provisions of collective security” (Nau, p.127). Obviously, with WWII as a result, the League of Nations failed, however, it did demonstrate effective communication leading up to the war. A more notable communication in WWII was the D-Day Ghost Transmission which was an effective form of secret telegrams that detailed the invasion on Normandy Beaches but, some telegrams were faked to throw off the Germans. “To support the deception, British intelligence agents had spread hints of a Calais invasion so convincingly that the Germans believed they had discovered a great military secret” (Nilsson, 2014). This timely and effective communication between President Eisenhower and Allied leaders helped win the war.
Finally, the Cold War, which I would consider this war to be based on communications since there was not an actual use of arms. The United States and the Soviet Union were able to effectively communicate using diplomacy and mediation causing the Cold War to be settled without the use of weapons. This caused both sides to agree on the number of nuclear weapons owned without bloodshed.
Nau, Henry R. Perspectives on International Relations: Power, Institutions, and Ideas, 6th Edition. CQ Press, 20180130. VitalBook file.