2. Britain’s Entry After the Invasion of Belgium
In August 1914, Germany’s invasion of Belgium violated the 1839 treaty guaranteeing Belgian neutrality, to which Britain was a signatory. Britain issued an ultimatum demanding Germany withdraw its troops; upon refusal, Britain declared war on Germany on August 4, 1914. This decision transformed the conflict from a European dispute into a global war, as Britain’s vast imperial resources and global influence were now mobilized against the Central Powers. (iwm.org.uk)
