Duke Katsura Tarō (桂 太郎, 4 January 1848 – 10 October 1913) was a Japanese general within the Imperial Japanese Army, and a politician who remains the longest-serving Prime Minister of Japan to date, having served three terms from 1901 to 1906, 1908 to 1911 and 1912 to 1913.

Katsura was born into a samurai family from Hagi, Chōshū Domain (present day Yamaguchi Prefecture). As a youth, he joined the movement against the Tokugawa shogunate and participated in some of the major battles of the Boshin War that led to the Meiji Restoration.

The new Meiji government considered that Katsura displayed great talent, and sent him to Germany to study military science. He served as military attaché at the Japanese embassy in Germany from 1875–1878 and again from 1884-1885. On his return to Japan, he was promoted to major general. He served in several key positions within the Imperial Japanese Army, and in 1886 was appointed Vice-Minister of War.

During the First Sino-Japanese War (1894–1895) Katsura commanded the IJA 3rd Division under his mentor, Field Marshal Yamagata Aritomo. During the war, his division made a memorable march in the depth of winter from the north-east shore of the Yellow Sea to Haicheng, finally occupying Niuchwang, and effecting a junction with the IJA 2nd Army which had moved up the Liaodong Peninsula.

After the war, he was elevated with the title of shishaku (viscount) under the kazoku peerage system. He was appointed 2nd Governor-General of Taiwan from June 2, 1896 to October 1896.

In successive cabinets from 1898 to 1901, he served as Minister of War.

Katsura Tarō served as the 11th, 13th and 15th Prime Minister of Japan. He remains the longest-serving Prime Minister of Japan to date.

Katsura became Prime Minister for the first time on June 2, 1901, and he retained the office for four and a half years to January 7, 1906, which was then a record in Japan. Japan emerged as a major imperialist power in East Asia. In terms of foreign affairs, it was marked by the Anglo-Japanese Alliance of 1902 and victory over the Russian Empire in the Russo-Japanese War of 1904-1905. During his tenure, the Taft–Katsura agreement, accepting Japanese hegemony over Korea, was reached with the United States. Katsura received the Grand Cross of the Order of St Michael and St George from British King Edward VII and was elevated to the rank of marquess by Emperor Meiji.

In terms of domestic policy, Katsura was a strictly-conservative politician who attempted to distance himself from the Diet of Japan and party politics. His political views mirrored that of Yamagata Aritomo in that he viewed that his sole responsibility was to the Emperor. He vied for control of the government with the Rikken Seiyūkai, the majority party of the lower house, headed by his archrival, Marquess Saionji Kinmochi.

In January 1906, Katsura resigned the premiership to Saionji Kinmochi over the unpopular Treaty of Portsmouth (1905), ending the war between Japan and Russia. However, his resignation was part of a "back door deal," brokered by Hara Takashi to alternate power between Saionji and Hara.

On April 1, 1906, he was awarded the Grand Cordon of the Supreme Order of the Chrysanthemum.

Katsura returned as Prime Minister from July 14, 1908 to August 30, 1911. His second term was noteworthy for the Japan–Korea Annexation Treaty of 1910. He also promulgated the Factory Act in 1911, the first act for the purpose of labor protection in Japan.

Katsura was increasingly unpopular during his second term over public perception that he was using his office to further both his personal fortune and the interests of the military (gunbatsu) over the welfare of the people. He also faced growing public dissatisfaction over the persistence of the hanbatsu domainal based politics.

After his resignation, he became a kōshaku (公爵 = prince), Lord Keeper of the Privy Seal of Japan and one of the genrō.

Katsura's brief reappointment again as Prime Minister again from December 21, 1912 to February 20, 1913 sparked widespread riots in what became known as the Taisho Political Crisis. His appointment was viewed as a plot by the genrō to overthrow the Meiji Constitution. However, rather than compromising, Katsura created his own political party, the Rikken Dōshikai(Constitutional Association of Allies) in an effort to establish his own support base.

However, faced with a no-confidence motion, the first successful one in Japanese history, and the loss of the support of his backers, he was forced to resign in February 1913. He was succeeded by Yamamoto Gonnohyōe.

Katsura died of stomach cancer eight months later on October 10, 1913, aged 65. His funeral was held at the temple of Zōjō-ji in Shiba, Tokyo and his grave is at the Shōin Jinja, in Setagaya, Tokyo.

From the corresponding article in the Japanese Wikipedia