<P> The ostensible reason given was that Britain was required to safeguard Belgium 's neutrality under the 1839 Treaty of London . The German invasion of Belgium was , therefore , the casus belli and , importantly , legitimized and galvanized popular support for the war . </P>
<P> The ostensible reason given was that Britain was required to safeguard Belgium 's neutrality under the 1839 Treaty of London . The German invasion of Belgium was , therefore , the casus belli and , importantly , legitimized and galvanized popular support for the war . </P>
which factor most directly resulted in great britain entering world war i
which factor most directly resulted in great britain entering world war i
German invasion of Belgium
German invasion of Belgium