Why did Allied forces occupy Tianjin in 1900?

In 1900, Allied forces occupied Tianjin primarily as a response to the Boxer Rebellion, a violent, anti-foreign uprising that sought to drive Westerners and their influence out of China.12

The occupation was driven by several critical factors:

• Escalating Violence: By 1900, the Boxers were actively attacking foreign missionaries and Chinese Christians. In June, an international relief force attempted to travel from Tianjin to Beijing to protect besieged foreigners, but they were blocked by imperial forces and forced to retreat.13
• Strategic Necessity: To restore access between the coast and the capital, foreign powers seized the Dagu forts on June 17, 1900.1
• Renewed Antiforeign Demonstrations: The city of Tianjin itself became a focal point for antiforeign sentiment, leading Allied forces to shell and occupy the city to suppress the uprising and secure their interests.2

This military action resulted in the destruction of the old city wall and was part of a broader international effort to relieve the siege of foreign legations in Beijing.12