Although General Arthur MacArthur Jr., commanding in the Philippines, was reluctant to weaken his already overextended forces, he agreed to dispatch to China the 9th Infantry Regiment, which departed from Manila on June 27 aboard USAT Logan.
[2] On June 17 the United States Navy's China Squadron under Rear Admiral Louis Kempff declined to join foreign naval forces in the Battle of Taku Forts, which guarded the river approach to Tianjin.
By early August a multinational coalition of 19,000 soldiers, including British, French, Japanese, Russian, German, Austrian, Italian, and American troops, was ready to move out of Tianjin toward Beijing, some seventy miles distant.
The Russian contingent prematurely forced an entrance into the Outer City on 10 August, only to be ambushed by waiting Chinese soldiers and require rescue by other allied troops.
In the seizure of the Outer City of Beijing on 14 August, elements of the 14th Infantry scaled the Tartar Wall, planted the first foreign flag ever to fly there, and opened the way for British units to relieve the legation compound.
Then on 15 August, Captain Henry J. Reilly's Light Battery F of the U.S. 5th Artillery shattered the gates leading into the Inner City with several well-placed salvos, opening the way for the allied troops to occupy the center of Beijing.
Although American troops had suffered comparatively light losses—slightly more than 200 killed and wounded—they did not take part in subsequent military operations, which consisted primarily of suppressing scattered Boxer elements and rescuing foreigners in the provinces.
This agreement also provided that the powers maintain a fortified legation in Beijing, garrison the Tianjin-Beijing Railway—an American contingent served as a part of this force until 1938—and receive reparations of $333 million.
In a few years it became apparent that even this sum was more than was needed to indemnify claims of American nationals and in 1907, and again in 1924, the United States returned portions totaling nearly $17 million to China, which placed the money in a trust fund for education of Chinese youths in both countries.
The participation of the United States in the Boxer Uprising marked the first time since the American Revolution that the country had joined with other powers in an allied military operation.
The intervention in China represented an instance of the gradual change taking place in the traditional policies and attitudes of the United States in world affairs as a result of the triumph of imperialism.
Developments in the early years of the 20th century would demonstrate, however, that the nation had to make changes and adjustments in many long-established institutions and policies—including those relating to military defense of the country—to meet the requirements of its new status as a world power.