To the right is a map of the countries involved in World War I with beige coloured countries being neutral.
Following the assassination of Franz Ferdinand and after Austro-Hungary's declaration of war on Serbia two groups, France, the UK and Russia formed the Triple Entent and the German Empire, Italy and the Ottoman Empire formed the Triple Alliance. Afer Austro-Hungary declared war on Serbia Germany invaded Luxembourg and Belgium which resulted in Britain declaring war on Germany. Then Austro-Hungary invades Russia. Colonies or allies of these countries subsequently declared war on the opposing countries and then the USA, India and more countries got involved.