During the start of World War II in September 1939, up until the end of 1942, Germany was generally successful on the battlefield and usually advancing.

Reasons for this success include the fact that Germany was better prepared due to re-armament and introducing conscription in 1935, before the Allies. Due to Germany's sheer hatred of the Treaty Of Versailles, they became psychologically prepared for war, where as Britain and France were putting of the idea of war by following appeasement.Britain and France were wary of each other in the early stages, so that made them uncoordinated in their opposition and made them easier targets fighting as individuals and not together. Also Germany hade better tactics, the use of blitzkrieg or 'lightning War' smashed the enemy's defences with a sudden, combined attack of aircraft, tanks and infantry, destroying air forces, railways, factories and power stations.

It was so successful because, countries like Poland, with the speed in which they attacked, without their air force or communications she could not defend herself.Defeats of the allies, such as France, left the people completely and utterly demoralised which gave the people no will to fight back against the Germans. The phoney war gave Germany time to re-group and rearm. However the Germans success did not continue, by the beginning of 1943 Germany was usually unsuccessful on the battlefield and generally retreating. This is due to certain factors and turning points that passed the success to the allies. One of the most, if not the most, important factors for the change was Germany's defeat at Stalingrad.

On 22nd June 1941 Germany had invaded the Soviet Union, but due to harsh weather conditions and their 'scorched earth' plan they were forced to retreat when the Russians began to attack. Stalin's 5-year plans taught Soviets to implement great changes and put in hardship so moving Russia's production factories East, away from the Germans was not a problem. The Soviet Union used resources sensibly to produce reliable weapons in mass amounts like the T34 tanks. The Soviet Union's industrial might eventually outweighed the Germans and so did their number of soldiers.In early 1942 Hitler's top generals wanted to surrender and bring their armies back but Hitler refused and the generals were replaced. Where as Stalin had learnt from his mistakes and followed the advice of his generals.

As Hitler had been making more of the decisions himself, he was blamed for the failures and people lost faith in him. In November the Soviet armies broke through North and South of Stalingrad, and surrounded the Germans. Hitler still said that they could not retreat and this lead to 150,000 Germans being killed, later Hitler's general went against orders and surrender.Because Germany had lost so many men it meant that they were considerably weakened and they could not recover from these losses which contributed to them losing the second world was. Up until then the Allies' thought Germany were un-defeatable but Stalingrad disproved this and so the Allies' morale lifted and made them fight and work harder. Another turning point in the Soviet Union was the Battle of Kursk, as the Germans lost so many men and tanks that they could never again mount an offensive attack on the Eastern Front.

From the on the soviets slowly but steadily began to drive back the Germans back to the frontier. In the beginning the Allied victories such as Dunkirk, gave the British people a huge morale boost as they survived to fight another day. The Battle of Britain and then the Battle of the Atlantic gave the allies control of the air and the sea, which made the reinvasion of Europe possible. The Battle of El Alamein was significant to the Allies, as the Germans there forth did not have control of Suez Canal and consequently the oil.The Allies now were able to invade through Sicily. One of the long-term factors that lead to the change and eventually Germany's defeat was Hitler's mistakes.

These include that he kept control of the war in his own hands; the success of invading France via the Ardennes made him over confident. There was an inefficient weapon supply, with Germany producing a wide range over weapons such as, 425 types of aircraft, compared to the Allies' mass production of a small range.Hitler failed to follow through, he could have defeated Britain twice; during the Battle of Britain and Dunkirk. He made rash decisions that had been successful at the beginning of the war due to lucky circumstance. Yet one of the most major mistakes Hitler made was to declare was on the USA after Japan bombed Pearl Harbour in 1941.

On 7th December 1941 the USA joined the war effort. She had a huge amount of resources so the allies did not run out. She helped with money, production and had good technology. She boosted the power and the number of allies in the war as well.

The USA helped Britain immensely during the battle of Britain, with new inventions they could find and destroy U-boats, like 'Huff- Duff' of special help to the allies was the discovery of an 'Enigma' coding machine which allowed the to decipher the secret 'ultra' codes which were used to send orders to the U-boats. Although the U-boats continued to hunt allied convoys for the rest of the war, the May 1943 sinkings of 41 U-boats were a turning point and a long-term factor to the defeat of Germany. The Germans had failed to cut Britain's supply lifeline across the ocean, which meant that they could now get supplies.Also with the Battle of Britain earlier in 1940, this meant that the British, with the help of the USA could retain control of both the air and sea. The fact that the Allies had won the Battle of the Atlantic meant that France could be re-invaded on D- Day with the help from the economic might of USA.

Operation Overlord took place on June 6th 1944, code named D-Day. An assault force of 4000 ships and landing craft carried 176,000 soldiers and their equipment across the English Channel. After fierce battles they broke through the coast defences and advanced inland.By September the allies had driven the German's out of France. The resistance groups also played a part during D-Day by relaying important information to the allies, which was vital for the success and destroying German communications.

The work of the resistance movements in the various occupied countries were not necessarily a main factor but generally 'weakened' Germany. Their acts of sabotage caused disruption to the German war effort causing them to divert resources that could have been used elsewhere, 140,000 German soldiers kept tied up in Yugoslavia.The air war is another factor that led to the change of the allies forcing the Germans to retreat as the RAF and United States Air Force dropped a total of 207,000 tones of bombs onto Germany, which resulted in Germany being forced onto defence production like fighters, anti- aircraft guns instead of offensive productions like tanks and artillery. The Germans bombed the British ports and cities in 1943; they only dropped 2,320 tones of bombs on Britain.

Overall this slowed down the German industrial production rate, weakening them further.All the factors, whether long or short term played a part in the change from Germany's advancing and the success on the battlefield to their downfall from 1943 onwards. However, some factors are undoubtedly more important or significant that others. It is questionable whether the Soviet Union and the war effort of the USA are as equally important. This is because when looking at the invasion of the Soviet Union, millions of Germans had dies, 200,000 had been taken prisoner at Stalingrad alone.

The Soviet Union was too big, the weather was appalling and Hitler had taken on a country that industrially overtook him in time.The USA may just come a very close second, due to its economic might, she recruited millions of men and since her entrance into the war it was just a matter of time until the Allies won. Yet saying that, if those two factors stood alone they may have not defeated Germany. The others, not such major factors but nether the less important, such as the resistance groups that helped to 'weaken' Germany so the defeat would come quickly.

As Napoleon's political life ended at Waterloo, but the decisive turning point was his defeat at Moscow. Hitler was soon treading Napoleon's road, and it is the Battle of Stalingrad that sealed his doom.