World War I started in July of 1914, and ended in November of 1918. The cause of this war was simply because of the assassination of Austria's Archduke Ferdinand. After that event occurred Europe divided into two sides, there was The Triple Alliance, which consisted of Germany, Austria-Hungary, and Italy. On the other side there was the group known as The Triple Entente, which consisted of Britain, France, and Russia. The Triple alliance formed because for one Germany and Austria-Hungary both spoke the same language and had mutual interest, and Italy which had feared the German country because of their powerful army, and thought they would be better off choosing to fight on what they thought was the stronger side. The Triple Entente came together because they had a mutual understanding, hence the name Entente. We could also say that the Alliance was more structured because their agreement was that if one was attacked then the other countries must aid them whereas the Entente was on the same side but didn't agree that one must help the other if attacked by Alliance forces. That kind of put them at a disadvantage because they had to fight knowing that they might not have the aid they need which could mean being over run easier by the Alliance but they had an understanding that each would support the other. .
Britain owned a lot more territory than Germany, which is why it was known as Great Britain. They always knew that Germany needed a large standing army because the country was more land based whereas Britain an island, had a more powerful navy. Germany sought to make a powerful navy as well even though they had a small coastline. Britain didn't like the idea of Germany pushing towards this more powerful navy as well as trying to acquire more territory to compete with them. This caused more tension between the two. After the long fought war the peace treaty was signed in 1919 known as the Treaty of Versailles.