The Imperialist countries like England and France had followed a policy of non intervention, appeasement towards the fascist aggression's of Germany and Italy. They believed that diverting the aggression towards communist and socialist countries like USSR, China would be beneficial to them. However the non aggression pact between Germany and USSR led the Imperial powers to form a different strategy as fascist powers were now threatening democratic countries like Poland, Turkey.
After the First World War, East Prussia had been separated from rest of Germany and city of Danzig was now between Germany and East Prussia. Hitler demanded that this city be returned to Germany. However when England refused to accept this demand the German armies marched into Poland and captured it in three weeks as no aid reached it. France and England now declared war on Germany.
In spite of the declaration of war, no actual fighting took place from 1939 September to1940 April when Germany attacked Denmark and Norway. USSR attacked the independent states of Latvia, Estonia and Lithuania, Moldova. It was believed that this was a part of the Non aggression pact between USSR and Germany.
German armies now marched towards Norway, Denmark and conquered it. Quisling, Leader of Norway's Fascist Party collaborated with the invaders of his own country. With Denmark, Norway in control Hitler set sights on Belgium, Holland and France. The battle of Belgium and Holland was completed within 1 month. In 1 week even the French government had surrendered meekly and half of France was given to Germany. The rest was to be used for disbanding the French army and providing supplies to support the Germans.
The Battle of Europe had been won and now Germany had become the dominant force in Europe. Now Hitler set his sights on Britain the last resistance to his ambition of becoming a European superpower.
The Wartime PM was Winston Churchill who declared that Britain would fight till the last drop of blood is spilled. The British Royal Air Force now had a mammoth task of countering the air superiority of Luftwaffe [German Air Force] and attacking it in Europe. With the Battle of France over the German force was concentrating on Britain.
In this crucial time the defeat of Britain would have ended the resistance in Europe. however the Royal Air Force successful defended Britain and attacked German bases in Europe forcing Hitler to postpone his attack on England.
This was a turning point of the War and the first serious challenge to German army. German armies now focused on North Africa and Balkans. The Italian army was repulsed from there but the Germans successfully captured both these regions.
The Non aggression pact was violated by Germany by attacking the Soviet Union. Hitler always coveted the vast natural resources of USSR and attacked it. He estimated that the Battle for USSR would be over in 8 weeks but he underestimated the strength of the Russian forces.
Although the German armies initially advanced and inflicted damages on key territories but the onslaught was halted soon. US - Britain and USSR promised full support to each other and agreed not to sign a peace agreement individually.
This cooperation of the two powerful opposing blocs resulted in a victory for the allies.
The US and Japan were in negotiations for their difference in South Asia. Japan along with Germany and Italy was a member of the Anti-Comintern pact. It recognized Germany and Italy as the leaders of the New Order and was in turn recognized as the leader of the New Order in Asia.
In spite of the ongoing negotiations, Japan attacked the American fleet stationed at Pearl Harbor in Hawaii. The US Navy suffered a huge defeat and as warships, aircrafts and personnel were lost. It is estimated that 3000 soldiers died.
USA declared war on Japan and Germany, Italy declared war on USA. With the entry of USA the countries of American continents too joined the allied forces.
After destroying the US Naval base Japan saw huge victories in colonial possessions of European countries and it had reached borders of Indian subcontinent.
Thus in middle of 1942 the Axis Powers were at a peak.
In 1944, the Allied soldiers had entered Germany. Russian army had entered Berlin in 1945, with Berlin surrounded Hitler committed suicide in May 1945 and Germany surrendered unconditionally. The hostilities ended on 9 May, 1945.
The war in Asia continued as Japan was still in control of large parts of China and Korea. British and US armies had captured the South Asian territories. Soviet army was launching operations in Manchuria and Korea. The Atom bomb, deadliest weapon of the war was used against Japan twice and the city of Hiroshima and Nagasaki were obliterated.
Japan surrendered soon and the Second World War was over.
The Second World War the most damaging war in the history of mankind. It had caused los of about 5 crore lives and 2.8 crore were civilians. The population of Germany, Poland was killed in war was 10%, in absolute terms Soviet Union lost 20% of its population.
In Fascist countries a war to exterminate Jews was started and around 6 million were exterminated in concentration and death camps. The extent of damage done to Economy of the World was a staggering $!0 trillion dollars.
US and scientist from other parts of the world who had come to US fleeing fascist aggression helped build the atomic bomb during the Manhattan Project. It was believed that Germany too was experimenting such kind of weapon. The atomic bomb was tested after German surrender and the team who developed it appealed to US to not use it. But US used it against Japan and this weapon killed about 3.2 lakh people. the damage done to next generations in these areas is still present.
It was argued that this weapon was used to stop the war immediately and prevent human loss.
The War had a few positive after effects as many international organizations have come up to promote harmony and peace. Such kind of war isn't imaginable today. Many countries saw freedom movements peaking and achieved their independence after the war.