Britain had regarded France and Russia as its most dangerous rivals at the time.
Meanwhile, Britain’s real ally was Japan at the time.
The main event of Militarism causing World War one was the naval rivalry which was made after 1900. The new Keiser Wilhelm announced his intention to build a bigger German navy than Britain. Germany’s navy was much smaller than Britain’s navy but the British army was put all over its colonies so they can be protected.
Germany didn’t have a big Empire like Britain but most people agreed, at the time, they were the best trained and the most powerful.
The Kaiser felt he needed a bigger navy than Britain to protect its country.
While Britain and Germany built up their navies, the major powers on mainland Europe were also building up their armies.
This is because big armies become potential threats to other countries, other countries started forcing alliances in order to secure land.
Imperialism was a cause because building an empire needs manpower such as an army and a navy to conquer and keep the land that they colonised.
The problem for Germany was that if the war broke out they would have to fight both Russia and France at the same time. On the other hand, Russia could put millions onto the fields and France had a plan of attack which was to change across the frontier and attack deep into Germany, forcing surrender.
Britain and France were working closely together with commanders which meant their military plans were designed to achieve quick victory.