I don't feel confident getting into world war II, but I can explain how world war I began.

Germany was a newly formed country, and after the Franco-Prussian war, needed to make allies as much as possible. Under the Chancellor Bismarck, Germany succeded to establish a number of treaties, isolating France, thus leaving France powerless.

When Kaiser Wilhelm II came into power, he forced Bismarck into resignation and let the treaty with Russia lapse. Russia quickly allied with France and soon there were two rival camps.
France and russia formed the Dual Entente, while Germany, Austria-Hungary, and Italy formed the Triple alliance.

Germany was afraid of the possibility of war on two fronts, from France and Russia, so the schlieffen plan was developed. Based on the idea that Russia would take a very long tiem to mobilise all of her troops, Germany would invade france first, passing through Belgium, a neutral nation, to avoid the well fortified French-German border. This becomes very important later.


In the Balkan states, known as the powder keg of Europe, there quickly developed conflicts between Serbia and Austria-Hungary. When Archduke Franz Ferdinand, the heir apparent to the throne of Austria-Hungary paid a visit to Serbia, a terrorist group known as the Black Hand plotted his assasination. Despite comple incompetence on the part of the terrorists, Ferdinand was very stubborn that he would not seek any kind of protection, and even after a failed bombing, the assasination went foreward.

Austria-hungary made sure that Germany would back them in the event of war with Serbia and russia, which had interests in the region and would back up serbia if war were to occur, and recieved a "blank check", meaning indefinite support. A-H sent an ultamatum to Serbia, which was agreed to with the exception of one single clause. Serbia nonetheless declared war.

Russia then began mobilising her troops to back Serbia. Germany sent an ultamatum to Russia demanding that she demobilize. Russia declined and Germany declared war. Germany then sent an ultamatum to France that she not support Russia. This was also declined, and Germany declared war on France. The Sclieffen plan relied on passage through Belgium, which was still a neutral country. Germany sent an ultamatum to Belgium that she allow passage of German troops. Belgium declined, and Germany invaded. This is when Britain entered the war, having her own interests in maintaining Belgium's neutrality.

There are other incidents and ideas of note, but these are as far as I can remember the most important things to keep in mind.