On 24 February 2022, Russia invaded Ukraine in a major escalation of the Russo-Ukrainian War, which began in 2014. The invasion has likely resulted in tens of thousands of deaths on both sides and caused Europe's largest refugee crisis since the Second World War, with an estimated 8 million people being displaced within the country by late May as well as 7.7 million Ukrainians fleeing the country as of October 2022. Within five weeks of the invasion, Russia experienced its greatest emigration since the 1917 October Revolution. The ongoing invasion has also caused global food shortages. This book tries to shed light on the causes which led to this war. It presents the historical background of the conflict and the military actions during the war.