After the war, Abe graduated from theImperial Japanese Army Academy in November 1897. Commissioned a second lieutenant the following 27 June, he was promoted to lieutenant in November 1900 and attended the Army Artillery School, graduating in December 1901. Promoted to captain in November 1903, he enrolled in the 19th class of theArmy War College, graduating in November 1907. Theultranationalist GeneralAraki Sadao was one of his classmates.
Abe was promoted to major in December 1908, becoming an instructor at the Army War College in September 1909. In November 1910, he was posted to theGerman Empire as a military attaché at the Japanese embassy and became a supplementary attaché at the embassy in Vienna in February 1913.
Abe was promoted to lieutenant colonel in February 1915 and to colonel on 24 July 1918. He served as the commander of the 3rd Field Artillery Regiment from 1918 to 1921. In August 1918, his regiment was sent to Siberia during Japan'sSiberian Intervention but never saw combat. He became secretary of the Army War College on 3 June 1921, and was promoted to major general on 15 August 1922. Appointed Director of the General Affairs Division of the Imperial General Staff on 6 August 1923, following the devastating earthquake of 1 September, he was placed in charge of overseeing martial law for the Kanto region on 3 September.
He was appointed director of military service affairs in the Army Ministry on 28 July 1926 and was promoted to lieutenant general on 5 March 1927. He later served as chief of the Military Affairs Bureau and asVice Minister of the Army, which he had been appointed as on 10 August 1928. He commanded the4th Infantry Division from 22 December 1930.
In January 1932, Abe was appointed to command theJapanese Taiwan Army and was promoted to fullgeneral on 19 June 1933. After serving on theSupreme War Council, he was placed on the reserve list on 10 March 1936.
Abe was not the obvious first choice asprime minister after the collapse of theHiranuma Kiichirō cabinet. From the civilian side,Konoe Fumimaro orHirota Kōki were regarded as front-runners, but the Army and the ultranationalists strongly supported GeneralUgaki Kazushige. AftergenrōSaionji Kinmochi declared his lack of enthusiasm for any of those candidates, the Army was poised to have its way. However, Ugaki fell ill and was hospitalized. The interimWar Minister General Abe was a compromise choice. He had the advantage of belonging to neither theTōseiha nor theKodoha political factions within the Army and was also supported as a relative political moderate by theImperial Japanese Navy. On the other hand, he was despised by many senior Army officers for his total lack of any combat experience.
Abe became Prime Minister on 30 August 1939.[3] He concurrently held the portfolio ofForeign Minister. During a reign which lasted only four months, Abe sought to end as quickly as possible theSecond Sino-Japanese War, and to maintain Japan'sneutrality in the growing European conflict. He also opposed to efforts by elements within the Army to form a political-military alliance withNazi Germany andFascist Italy. Increasingly lacking in support from either the military or the political parties, Abe was replaced byMitsumasa Yonai in January 1940.
Abe as the Japanese ambassador signing the Japan-Manchukuo-China joint declaration withWang Jingwei andZang Shiyi, 30 November 1940 in Nanjing
Three months later after his replacement as Prime Minister, Abe was sent by the army as a special envoy toChina to advise theJapanese-supported regime ofWang Jingwei inNanjing and to negotiate a treaty ensuring Japanese economic and military rights innorthern China. However, he had some sympathy for Wang's Reorganized National Government. Abe remained as the Japanese ambassador to China in Nanjing until December 1940.[4] After his return to Japan, Abe joined theHouse of Peers in 1942, and accepted the largely-ceremonial position as president of theImperial Rule Assistance Political Association. He was appointed the 10th (and last)Governor-General of Korea in 1944 and 1945.