In my opinion it was due to the poor leadership and planning that caused Germany to loose the First World War. The breakdown of the Schlieffen plan that was supposed to be foolproof and Kaiser Weilhelms reluctantly to involve his rich friends in industry that caused them to loose the war. The failure of alternative strategies, the submarine warfare, and the final collapse of Germany's final offence were only results of previous failures.
It was hardly any surprise that the Schlieffen plan failed. The plan was to surround Paris by going through Belgium in the hope that Russia would take a while to mobilise.However, this plan was decided considerable time before the tart of the war. Things had changed and Russia was quicker to mobilise than originally thought. What Germany also didn't realise was the England had an agreement with Belgium from the beginning of the nineteen hundreds that if Belgium was under attack England would intervene and assist.
Germanys failure to realise this and not have a back up plan just in case, left them doomed from then on. If the Schlieffen plan had not failed then there would have been no reason to need back up plans. However it did fail and the alternative strategies also failed.It is possible that if Germany had an effective alternative plan then they could have gone on to win. One of these backup plans was submarine warfare to bring Britains navy down. Britain suffered catastrophic losses but the introduction of the convoy system proved decisive in reducing their losses.
By 1918 it was seen that Germany were loosing the submarine war. Then the USA declared was in April 1917, which was the final kick in Germany's teeth. After fighting for three years and then a new large and fresh army arrive it meant testing Germany's limits and making them work even harder.However the main reason that germane lost the war was the limitations of German economic mobilisation. The economy was not backing the war effort. Due to the submarine warfare and the blockades that were put on German docks, banking and exportation was badly disrupted.
This meant that Germany was unable in import and export goods like oil, rubber, metal and mercury, fats and fertilisers that were essential in the manufacture of weapons and ammunition, as well as food. Where German oppositions had the factories and industries in their country manufacturing goods that were needed for use in war, Germany had not.The owners of the factories were rich and powerful friends of Kaiser Weilhelm whom he did not want to loose by forcing them to produce war materials. He also did not want to loose these friends by raising taxes.
As a result of this there was no imports, export, manufacture of war materials, or money to pay for it. There was not enough food for all the soldiers and the rest of society so they began to resent the war. In 1917 Germany and Russia negotiated peace (the Treaty of Brest-Litovsk). Germany left 1. 5 million troops on eastern fronts to maintain control over Russia.However, Germany underestimated military strength of opponent's forces on the western front.
In September 1918 Germany was faced with the threat of invasion and on 29th September the war was lost. The collapse of Germany's final Offensive was inevitable from the start. In conclusion, the most influential reason in bringing about Germanys defeat was the limitations of German economic mobilisation. Despite the other factors that went wrong for Germany, with more equipment and preparation from the economy, they would have definitely have had better chances.
The next factor is the failure of the Schlieffen plan and entry of the USA. Better tactics and less "interference" from other countries would have resulted in more success. However with more preparation from the economy they may have able to cope with these set backs. The collapse of Germany's final offensive probably comes next because it was the factor that actual ended the war.
The finally the failure of alternatives strategies because had the first plans worked there would be no need for other strategies. Hence they would not have failed.