He studied Western military science under Ōmura Masujirō and was a company commander defending the domain against the Second Chōshū expedition mounted by the Tokugawa shogunate.
He subsequently served in the Boshin War of the Meiji restoration. In 1872, he entered the fledgling Imperial Japanese Army as a captain. In February 1874, Sakuma participated in the suppression of the Saga Rebellion, during which time he led a column of troops from Kumamoto Castle.
The then participated in the Taiwan Expedition of 1874.
During the Satsuma Rebellion, he was commander of the IJA 6th Infantry Regiment. In February 1881, Sakuma was promoted to major general in command of the Sendai military district.
In May 1885, Sakuma was given command of the IJA 10th Infantry Regiment and promoted to lieutenant general the following year. The same year, 1886, he was elevated to the title of danshaku (baron) under the kazoku peerage system.
With the outbreak of the First Sino-Japanese War, Sakuma commanded the IJA 2nd Division at the Battle of Weihaiwei, and later served as Japanese military governor of Weihaiwei in Shandong Province, China.
At the end of the war, he was awarded the Order of the Rising Sun, and elevated to shishaku (viscount). In 1898, Sakuma was appointed commander of the central division of the Imperial Guardss, and became a full general. After a brief period on leave, he then became commander of the Tokyo Garrison.
With the end of armed resistance by Taiwan"s Han Chinese population, the colonial authorities turned their attention to the suppression of the mountain dwelling aboriginal tribes.
One of the reasons Sakuma was selected to head the colonial government was due to his participation in Japan"s previous 1874 campaign, and his mission was extend Japanese control into the aboriginal regions. During his tenure, Sakuma led several armed campaigns against the Atayal and Bunun peoples.
Sakuma was one of the longest serving Governor-Generals of Taiwan, stepping down in 1915, after having successfully completed his pacification campaign. He was highly regarded for helping develop Taiwan"s east coast, especially the port of Hualien, and the Taroko Gorge area.
He is also credited with introducing baseball to Taiwan in 1910.
The shrine in Japan still exists, and unsuccessful efforts have been made to reconstruct the one in Taiwan as well.