He was sent to Edo in 1857, and became active in the Sonnō jōi movement. In 1866, he was ordered by his domain to go to Nagasaki, where he met Gotō Shōjirō and Sakamoto Ryōma, who convinced him to meet with Saigō Takamori in Edo the following year, and to work for an alliance between Tosa and Satsuma.
Tani fought in the Boshin War to overthrow the Tokugawa shogunate, leading imperial forces in the north Kantō, and Aizu-Wakamatsu campaigns. After the Meiji restoration, Tani became a general in the Imperial Japanese Army, and helped suppress a number of samurai uprisings in Kyūshū, including the Saga Rebellion and Shimpūren Rebellion. He withstood a siege of 52 days in Kumamoto castle against Saigō Takamori during the Satsuma Rebellion. Tani also took part in the Taiwan Expedition of 1874.
Afterwards, Tani was commandant of the Imperial Japanese Army Academy before retiring from active service in 1881. Tani was one of the founders of the conservative political party, Chūseitō, in 1881. He also became president of the Gakushūin Peers’ School in 1884.
In 1885, Tani joined the first Itō Hirobumi cabinet as the first Minister of Agriculture & Commerce. In 1890, Tani was ennobled with the rank of shishaku (viscount) in the kazoku peerage system, and became a member of the House of Peers.
Tani's political views, as they became known in the 1880s and the 1890s were a mix of conservatism, liberalism and staunch anti-Imperialism.
Tani was one of the leaders of a group called the "conservative opposition", an alliance of retired generals, politicians and peers who were critical both of the Meiji government and the movement for popular rights. Leading members in the conservative opposition, including Tani, believed that the "nation" is composed of a mystical union between Emperor and people, and therefore the government should rest neither with the oligarchs nor with the political parties.
In his constitutional proposals, Tani had suggested to raise the Emperor to a status of an arbitrator between three independent branches of government - the executive, the judicial and the legislative, balanced by a set of checks and balances but dependent on the discretion of the Imperial Throne. Though critical as for the "selfishness" of the political parties, he was a supporter of the freedoms of speech and assembly.
Tani's views on foreign policy were a mix of anti-Imperialism and belief in Japan's national essence (Kokutai). On the other hand, he was set against any concession to the foreigners in the struggle against the unequal treaties and believed Japan must refrain from alliances with great powers in order to uphold its own unique culture, tradition and national essence.
Quotes from others about the person
“Japan's foreign minister, Mutsu Munemitsu: "lone flower in a field of grass."”