In the early 1850s, the European balance of power faced challenges with Russia's expansionist policies, particularly toward the waning Ottoman Empire. France, under Emperor Napoleon III, and Britain, concerned about maintaining their global empire and countering Russian influence, found common ground in their opposition to Russia. The crucial incident that precipitated the declaration of war was the dispute over the holy places in Jerusalem, which ignited deeper tensions between the Orthodox Christian Russians and Roman Catholics and Protestants supported by France and Britain.

By March 1854, diplomatic efforts to resolve the issues failed, leading both France and Britain to the conclusion that military intervention was necessary. France mobilized its troops swiftly, and on March 28, 1854, both nations formally declared war on Russia, marking the beginning of the Crimean War. This alignment of powers was significant as it demonstrated a unified European front against Russian expansionism, although their motivations stemmed from different geopolitical interests.

The Crimean War would eventually draw in various nations and witness significant battles, such as the Battle of Balaclava and the Siege of Sevastopol. This conflict highlighted the need for military reforms, leading to modernization in both British and French forces, and addressing the dire conditions that soldiers faced, especially chronicled by figures like Florence Nightingale. The war would last until 1856, resulting in a restructuring of power dynamics in Europe and leaving a lasting impact on military strategy and healthcare practices in wartime.