One of the main reasons why the Allies won was because they supplied munitions faster than the Germans could. They used 13 000 aircraft; 17 000 tanks; 19 000 parachutes and 1 000 000 bombs. Until Cherbourg was captured, the Allies relied on the two artificial harbours at Omaha and Gold. The British harbour proved very successful. It gave shelter to allied ships in the rough waters but the American shelter was destroyed by a three-day storm. The allies build the pipe line Pluto across the channel which supplied a million tonnes of fuel daily. The Germans were exhausted from the long war and they also had to fight against Russia.
On the 26th June, the Americans reached and with difficulty captured the important port of Cherbourg which was the 1st major objective for the allies because it was to give shelter for their supply ships. However Cherbough could not be used because it had been wrecked by the Germans. The British and the Canadians made heavy attacks near Caen.
The first phase of the battle went according to plan but not according to schedule for the allies because they were delayed by bad weather and tough enemy in Omaha. The second phase of the battle called “The battle of the Hedgerows”. The “bocage” countryside and the skilful German fighting delayed the American progress southwards. The Americans lost over 40 000 men. This was the worst phase of the campaign. After taking over Caen, Montgomary launched a huge attack (750) tanks which the Tiger tanks halted. Then huge loss of the “air battle” for the Germans took place. Not long after that Rommel committed suicide because he was involved in a bombing plot against Hitler. Then the Americans won at St-Lo and advanced towards the Avranches. Another army lead by General Patton arrived in Normandy and swept on in to Brittany and then R. Seine. The Ultra code-breakers gave the allies four days notice of a powerful German attack towards the Avanches (ordered by Hitler). The attack was stopped by the British and American air force. Then Patton formed a trap at the Falaise pocket but was not able to close it. Although most of the German panzlers got away the roads, the tanks, guns and vehicles filled the roads in the pocket. 60 000 Germans were captured or killed. The allies pushed towards Seine and Paris was liberated. The Americans and French who had landed near Toulon linked with Patton's troops. German strength in France had collapsed.
The main reason why the Second World War was won by the allies was that Hitler fought on more than one front. The D-day landings opened up a western front. It stretched the German army in two. That is why they had such a huge significance in the allied victory. The allies' defeat at Normandy meant that German strength in France had collapsed. This made Germany wide open for invasion. This invasion followed on the winter 1944-1945. D-day was the outcome of months and years of fighting and preparations. It was the decisive move of the allies, which occupied Germany and tried to match the Russian advance form the east. The D-day invasion of France did not change the outcome of the war because Germany was already losing it. It marked a "long awaited beginning of the last chapter of the war".
There were other reasons, which contributed to the allied victory. The British victory in the Battle of Britain was very crucial. After Hitler had occupied France in a Blitzkrieg, Hitler tried to end any problems in the West by invading the Britain. For such a victory, Germany needed to have air superiority. Although the German Luftwaffle was unprepared, they managed to almost beat the British Royal Airforce. However, Hitler made a huge mistake when he swapped the bombing form the airfields to London. The Royal Air Force recovered and the Western front remained open. Britain also avoided a crucial defeat in the battle of the Atlantic. The main reasons for this was because all through the war Germany never fully concentrated on Britain. Hitler was more concerned with defeating Russia (for living space) and therefore he turner the German attention and military power towards it. Also Britain received financial aid from the USA and munitions on the "Lend and Lease" policy.
Britain was an important ally. The British provided many men and munitions. They fought in the beaches of Gold and Juno. If Britain was defeated, the Americans would have needed many more men and munitions. Also Britain provided a base for the allied forces. If Britain had fallen, the USA would not have been able to land in Normandy. They will have had to land somewhere else where from where oil, men and munitions will have been difficult to supply or only bomb Germany which has been proved in wars such as Vietnam to be unsuccessful in achieving a complete victory. Having direct military pressure (ground troops) from the allies ensured an allied victory.
The days after D-Day were significant because that is when the advance in to France and later Germany took place. It was important that the British, Americans and Canadians while fighting in France had good military supplies. Things such as the pipeline Pluto and the two artificial harbours helped in the supplying of the munitions. The financial and military power of America and the fact that Britain was so near to France made it possible for this supply of munitions to take place.
British victories in North Africa in the earlier stages of the war ensured a good oil supply for the British which was crucial when leading a war and boost up Britain's morale.
America had contributed greatly to the allied victory. After the 1st World War, America was strongly isolationist. The reason why it joined the allies was the Japanese attack on Pearl Harbour which meant that America was at war with Japan. Japan had a military alliance with Germany and therefore Germany declared war on America. That is why America made a military alliance with Russia, Britain and Canada. Having the strongest country against her put Germany in a much weaker position. America was military and economically very powerful. They supplied most of the munitions, men and almost all the aircraft as well as providing plans from military intelligence.
Throughout the war Hitler had concentrated more on Russia than Britain, which gave Britain "breathing space" and helped them win in the "Battle of Britain". The Russians deserve half of the credit in the World War 2 allied victory. In the winter of 1944-45 the Red army made a great surge forwards and went in to Berlin. Berlin was surrendered after one weak of fighting.
This took place only because Russia survived both of Hitler's attacks. In mid 1941, Hitler tried to invade Moscow. The German army was not prepared for such conditions as the Russian winter and Hitler was overconfident. The German army was delayed (by Greece and Romania, which made them attack in the winter. The Russian army was caught by surprise and Russia had tremendous losses during the attack. However the Germans ware forced out by the rough winter, huge territory and supply of men. In the following summers of 1942, 1943, Hitler attacked Russia with all the forces his army still had. He aimed towards the crucial oil supplies of Stalingrad. A victory will have meant Germany had large supplies of oil, which was crucial in fighting a war. The German army was stopped by the fierce defensive fighting of the Russian line of defence. After these two battles, the Russian army moved form defence to attack and pushed the German army all the way back to Berlin. The most important battle between Russia and Germany was the tank battle of Kirsch where the Russians won not only because they had superiority in terms of size but also because they applied better tactics.
Russia created an Eastern front. This meant that Hitler's army had to be split in two to defend both East and West boarders at a time when it had been exhausted form attacks in Russia and Britain and America and Canada. Also there was another front Hitler had to fight on - the Italian front. This meant that the Germans had to fight on three fronts.
If the Germans had defeated the Western front, the Germans would have concentrated their army on Russia. It is possible that this would have caused a Russian defeat but it is most likely that the Russians would have been able to still defeat Germany from the east. I have come to this conclusion because at the time Russia had twice escaped German attacks, had won in Kursk and was advancing in to Germany. If Russia had alone defeated Germany, she would most likely go in to France and the whole Europe would turn communist (That is one of the reasons USA, Britain and Canada hurried to make the D-Day landings). It would still however mean that it was an allied victory because Russia was part of the allies. If on the other hand Russia had been invaded earlier on and Moscow and Stalin grad and the oil fields were taken, the Germans would have had a good oils supply and high morale. It would mean Germany's whole army could concentrate in the west. It is more likely that the western front would have been lost because of the difficulty of making landings in enemy territory. This makes Russia the most important factor in the allied victory. However all these factors combined together ensured the allied victory, which would have been more difficult to achieve if any one factor was absent.