Great Britain joined the dual entente in 1907 to form the triple entente. Archduke Ferdinand was assassinated by Serbian terrorists. This sparked the great war. One by one countries were dragged into the war until on August 4 1914 Britain helped to defend France against Germany. Due to the treaty of London, Great Britain had to help defend Belgium no matter what. They fulfilled that treaty. Their dedication to this treaty prevented Germany from taking control over all of Europe.
Britain contributed several weapons like the Mk 6 tank and the Lewis machine gun, they also sent 6 million men to the war when it did happen. Since Britain was mainly focused about sustaining their empire they fought a lot in Africa where the ottoman empire resided.
When the war broke out Winston Churchill was planing the naval campaign of Dardanelles and the military landing of Gallipoli. These failed and he was demoted. Because of this he resigned from Government. He signed up as an officer and fought in the war until 1916. He then got promoted to munitions manager where we looked after all the weapons and ammunition the British used. After this he was elected Secretary of state and war where he attend the peace talks of Paris. He never discussed peace but did discuss the after-war world.