Germany has to bare the most responsibility for causing WW1.

Introduction
To start, with we have to remember that there where many causes of first world war began like political, economical, social and military. One of very important reasons was assassinating archduke Franc Ferdinand in Sarajevo in 28 June 1914. System of alliance otherwise known as a "one thing led to another", show that all empires was responsible for beginning “Great war”, so we can’t blame only German as the only one who was responsible for starting this conflict. Of course Germany has a main value, not just because of the “blank cheque”. Also developments and historical processes, like Weltpolitik, Moroccan crisis’s and Balkans wars, from the beginning of XX century were significant in this situation.
Political changes and Weltpolitik
Political changes in Germany were very important. Left wing SPD(Social Democratic Party of Germany) made large gains in the 1912 German election. Government was still dominated by Prussian Junkers who were worrying about disastrous consequences of losing war, and even successful war may bring big economical looses like separate from other countries. Weltpolitik was a strategy adopted by Germany in late XIX century. It was more aggressive and that’s why resolute in conflict with foreign nations. Weltpolitik was a Wilhelm II plan, to made Germany large, strong, and unbeatable empire in every possible way. The biggest aspiration of Wilhelm II was to built a navy as strong as Britain’s or even stronger. In many ways, Weltpolitik was seen as a natural development springing from the nationalism that had influenced German history in recent years. Whereas before nationalism had focused on attaining the unification of Germany, when that was achieved German nationalists sought to increase Germany's international power, and a colonial empire was thought to be an essential part of this. The doctrine of Social Darwinism was popular at the time, and it stated that the idea of the survival of the fittest applied to states as well as individuals. If a state did not strive to expand, it would itself be weakened or destroyed. All this fed into the nationalism that already existed in Germany and prompted the greater expansionism that Weltpolitik represented.
“Blank cheque” and system of alliances
“Blank cheque” was offered to Austro-Hungarian, by Wilhelm the second, in terms of German support for every action that Austria-Hungary choose to punish Serbia for assassinating Franc Ferdinand. Austro-Hungarian throne was assassinated in his car during a drive in Sarajevo. The assassination was the work of a terrorist group known as the “Black Hand”. Austria sent an ultimatum to Serbia asking for “complete surrender” on 23rd July and Serbia agreed almost all articles of agreement, but Austria declared war on Serbia on the 28th of July 1914, which created a war that would split Europe, in two. One side was Triple alliance which was Germany, Italy and Austria-Hungary. Second side of this conflict was Triple Entente which include Britain, France and Russia. After that Russia bound by treaty to Serbia, decided to mobilize in her defense, but because of her huge territory this process was really slow and took about six weeks to complete. While this time Germany allied to Austria-Hungary declare war to Russia, on 1 August, as an act of war against them. France found itself at war against Germany and, by extension, on Austria-Hungary following a German declaration on 3 August. To avoid situation that Germany have to fight on two fronts, they quickly defeat France(Schlieffen plan), and to reach Paris by the shortest possible way they invade neutral Belgium. Britain declare war to Germany because of two reasons. First was treaty to France, but more important reason why Britain entered this conflict was that they were obligated to defense neutral Belgium in terms of 75-year old treaty. Like France, Britain was by extension also at war with Austria-Hungary. With Britain's entry into the war, her colonies and dominions abroad variously offered military and financial assistance, included Australia, Canada, India, New Zealand and the Union of South Africa.



Militarism
Militarism is not just an arms race, but also government’s seeking god reason for war. It could happen because of the influence on government made by the generals. All nations of Europe were militaristic, but the governments of Germany and Austria-Hungary were especially so. All European countries built up their armies and navies.
“In 1914, their armed forces stood like this:
• Germany: 2,200,000 soldiers, 97 warships
• Austria-Hungary: 810,000 soldiers, 28 warships.
• Italy: 750,000 soldiers, 36 warships
• France: 1,125,000 soldiers, 62 warships
• Russia: 1,200,000 soldiers, 30 warships
• Great Britain: 711,000 soldiers, 185 warships
As one country increased its armies, so all the others felt obliged to increase their armed forces to keep the ‘balance of power’”. Germany and Britain were competing over the size of their navies, in 1900 Kaiser Wilhelm began to built up the German navy. He wanted Germans to sail all over the World. After 1906, he began to build numbers of the new, large “Dreadnought” battleships which were more powerful than any other ship. Another important thing that empires of Europe did, was to train all their young men in case if they would be needed on the front line. “One historians has estimated the total number of men (including reservists) that the countries could thus call upon as:
• Germany: 8.5 million men
• Russia: 4.4 million
• France: 3.5 million
• Austria-Hungary : 3 million”
It was important to realize that, although in 1914 the German army was the biggest and best in the world. The Russian army was growing the fastest, and German generals were worried about that, in a few years time, they would not be able to defeat Russia so easily.

Why not only Germany
The reason why we should not put all responsibility for beginning war on Germany is that Austria-Hungary misunderstood meaning of “Blank Cheque”. They interpreted it as German recommendation to start warfare. We have to remember that all the major powers had a “plan”, and if not Germany, there is possibility that Russia would start the World War One. German may thought that attack will be the best way to defend themselves. Reason why they could feel unsaved was Russian mobilization which could be interpret as silent declaration of war. They have to do something to avoid fait on two fronts (Schlieffen Plan). If Germany would wait for Russian and French attack, their chance to win would be much more less. All empires wouldn’t try hard enough to avoid war, “Czar Nicholas II was communicating with Germany’s Kaiser Wilhelm in an attempt to avoid war. But his top military and political advisers were pushing for strong measures including war if necessary. Their pressure resulted in full Russian mobilization”. As it is showed, war was accepted as part of human activity. Public supported their political and military leaders in starting war. Only a few pacifist like Einstein were opposite.
Summary
To sum up, I Think that responsibility is in the middle, because Germany first declare war to Russia and France. Gave “Blank Cheque” to Austria-Hungary, which very often is interpreted as German allow to start war with Serbia, but on the other hand all empires were just waiting for responsible reason to start this conflict. That situation may be result of general mood for war, people just can’t see any other way to solve their problems. They still think that this war will be as fast as wars in nineteen century, and that’s why World War One was so huge shock for everyone. And the end of it was much later then it was expected. Nine million soldiers lost their live, conflict took place on Europe, Africa, Asia, Atlantic Ocean, Pacific and Indian Ocean. Ends by Entente wins, after this war empires of Germany, Russia, Austria-Hungary and Ottoman Empire do not exist anymore, but new countries was created e.g. Poland.
References:
http://historia.gazeta.pl/historia/1,98592,6488555,Przyczyny_wybuchu_pierwszej_wojny_swiatowej.html
http://www.answers.com/topic/causes-of-world-war-i#German_domestic_politics
http://www.firstworldwar.com
http://www.britannica.com/EBchecked/topic/639573/Weltpolitik