most likely because they were able to predict the future and knew hitler would kil them all anyway
They had alliances with countries that were involved.
Japan had early alliances with Germany. They were promised the Pacific Island holdings of the US if the Axis powers won the war.
Germany invaded Belgium that was neutral
No
There were no other alliances apart from the Triple Entente - Britain, France & Russia and the Triple Alliance - Germany, Austria-Hungary & Italy. They are were the only alliances involved not true Britain had an Alliance with Belgium and Russia had an Alliance with Serbia
Britain, Russia and France. Germany, Italy and Austria-Hungary.
Britain declared war on Germany on August 4, 1914 after Germany invaded Belgium.
Britain declared war on Germany on 3rd September 1939, two days after Germany invaded Poland.
In order to protect itself against other country's with their help. It works both ways in an alliance.
The two alliances of world war one where the allied power (Britain, France, Russia and later the united states) and the Central powers (Germany, Austria-Hungary and the Ottoman empire)
Germany and Britain
Germany, Italy(In the beginning) and Aurtria-Hungary beiong to The triple Alliance France ,Britain and Russia beiong to The triple Entente