There has always been a power a struggle amongst European nations. Imperialistic rivalries, system of alliances and militarism were wide spread through the entire region. These 4 factors were just a bomb waiting to go off , leading to the beginning of the first world war.
A lot of rivalries arose when European began to imperialise the continent of Africa . At first the tensions were relieved after the Berlin conference , when it was decided how Africa would be “carved up”. but tension later rose again sometimes even leading to small wars. In 1895 France and England engaged in some battle over territory in suddan , this was called the fashoda incident, and a few years later in 1889-1903 France and Germany engaged in the Boer war, which over the rights to South Africa.
After several disputes among the Europeans, many of them began to build up their armed forces. This is called militarism. Many nations believed that the only way settle disputes and higher nationalistic spirits is by improving your military so that it is stronger than that of anyone else. But what happen is that as one nation began to build up their military another nation would feel threatened and begin to build up their own. This was a recipe for disaster waiting t happen. This is exactly what between England and Germany. England, in the 1800’s and early 1900’s, England was known for its superior navy. They had the largest fleet and some of the most advanced technology of that time. It was nicknamed the “mistress of the sea”. This was until Germany decided to challenge England’s supremacy by build a great navy. In 1905 the Germans developed a new battle ship called the Dreadnought. These new ships made England’s navy inferior to that of Germany.
Many nations began to feel threatened by the increasing armed forces in Europe so they decided to seek another nation with common interests that would back them up in time of need. This was the system of alliances. Europe broke up into 2 parts, the central powers (Germany, Austria-Hungary, Bulgaria, and the ottoman empire) and the allied powers ( France, great-Britain , Italy, Russia, etc..). Even nations who have hated each other for ages allied with one another against a common enemy, like the saying goes: the enemy of my enemy is my friend. France and England for example have been enemies dating back many centuries but a common fear of Germany brought the two together in an alliance, at least for the time being.
I believe that the system of alliances was the factor that contributed the most to the cause of WWI. Since there were only to major powers in Europe at the time just one incident would be required to set off the war. All that was need was incident between a central power nation and an allied power nation, the allies of both nations would back that nation, which eventually would lead to powers fighting one another. That one spark that was needed to set off the war was the assassination of the arch duke ferdinand ( heir to the austria-hungary throne ). A-H belonged to the central powers but the assassin nation, Serbia, belonged to the allied powers. This created tension. Russia was backing Serbia and Germany backed up A-H. eventually everyone ended up fighting. You can clearly see if neither Serbia or A-H had allies their problem would have stayed within their country and not involve the rest of Europe.