British (Civ6)/Civilopedia

Great Britain’s participation in the Triple Entente (the military alliance between France, Great Britain, and Russia) was by no means a foregone conclusion. Longstanding military competition between France and Great Britain dating back to the time of Napoleon, as well as ties between the royal families of Great Britain and Germany made British participation in the Central Powers a plausible outcome. Ultimately Great Britain joined the Entente due to a quick rise in competition between Germany and Great Britain that saw many people seek checks on rising German power.
On the eve of World War I, there was no guarantee that Great Britain would send military forces into continental Europe. It was largely through the constant pressure of a small group of officers in both the French and British armies that saw Great Britain commit a small force to French soil. Indeed, the Kaiser himself was shocked that the British declared war on Germany, declaring that they had made a “foolish mistake” over a “mere scrap of paper.”