answers: 1 September 1939
context: North aided by Estonians hoping to re-establish national independence. This delay slowed subsequent Soviet operations in the Baltic Sea region. By late May 1944, the Soviets had liberated Crimea, largely expelled Axis forces from Ukraine, and made incursions into Romania, which were repulsed by the Axis troops. The Allied offensives in Italy had succeeded and, at the expense of allowing several German divisions to retreat, on 4 June, Rome was captured. The Allies had mixed success in mainland Asia. In March 1944, the Japanese launched the first of two invasions, an operation against British positions in Assam, India, and soon </s> goal of facilitating Army Group B's advance. The Allied command reacted immediately, sending forces north to combat a plan that, for all the Allies could expect, resembled the earlier Schlieffen plan. This move north committed their best forces, diminished their fighting power through loss of readiness and their mobility through loss of fuel. That evening French troops crossed the Dutch border. The French and British air command was less effective than their generals had anticipated, and the Luftwaffe quickly obtained air superiority, depriving the Allies of key reconnaissance abilities and disrupting Allied communication and coordination. While the German invaders secured </s> Africa and Asia. Most countries whose industries had been damaged moved towards economic recovery and expansion. Political integration, especially in Europe, emerged as an effort to end pre-war enmities and create a common identity. The start of the war in Europe is generally held to be 1 September 1939, beginning with the German invasion of Poland; the United Kingdom and France declared war on Germany two days later. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or even the Japanese invasion of Manchuria on 19 September
question: when did the allies enter world war 2