Adna Romanza Chaffee (14 April 1842-1 November 1914) was a US Army Lieutenant-General who served in the American Civil War, the Plains Indian Wars, the Spanish-American War, the Boxer Rebellion, and the Philippine-American War. He served as Chief of Staff of the US Army from February 1904 to February 1906, succeeding Samuel Baldwin Marks Young and preceding John C. Bates.
Adna Romanza Chaffee was born in Orwell, Ohio on 14 April 1842, and he served as a Union Army lieutenant during the American Civil War before fighting the Native American tribes of the Great Plains and American Southwest in the Plains Indian Wars. After the Battle of Big Dry Wash in 1882, he was brevetted Lieutenant-Colonel, and he became a cavalry colonel in June 1897. With the outbreak of the Spanish-American War in 1898, he became a Brigadier-General of volunteers, serving in the Cuban campaign.
In June 1900, he was sent to command the United States expedition to China during the Boxer Rebellion, taking part in the relief of Peking. His time in China led to him concluding that Asians respected only superior power, and, when he was transferred to the Philippines during the Philippine-American War, he combined benevolence and public health measures with force and cooperation with local officials. From July 1901 to October 1902, he served as military governor of the Philippines, and, from October 1902 to October 1903, he commanded the Department of the East.
From January 1904 to January 1906, he served as Chief of Staff of the US Army, and he retired in February 1906 with the rank of Lieutenant-General. He then moved to Los Angeles and was appointed to the Board of Public Works, and he died in 1914 at the age of 72. He was the father of Adna R. Chaffee Jr., the father of American armored warfare.