Umezu returned to China in May 1938 as commander-in-chief of the IJA 1st Army.
By this time, the IJA 1st Army had completed its combat operations, and was serving as a garrison force in Japanese-occupied northern China.
From September 1939 he was commander-in-chief of the Kwangtung Army, which was likewise acting as a garrison force in Manchukuo.
He was promoted to full general on August 1, 1940.

In July 1944, Umezu was appointed as the final Chief of the Imperial Japanese Army General Staff, and a member of the Supreme War Council, following the resignation of Hideko Tojo.
Along with Army Minister Korechika Anami and Chief of Imperial Japanese Navy General Staff,  Soemu Toyoda, Umezu opposed surrender in August 1945; he believed that the military should fight on, forcing the Allies to sustain such heavy losses in an invasion of Japan, that Japan could negotiate for peace under better terms.
He was aware of the planned coup d'état by junior officers opposed to the surrender, but did nothing to either aid or hinder it.
He was personally ordered by Emperor Hirohito to sign the instrument of surrender on behalf of the armed forces on September 2, 1945 and was thus the Army's senior representative during the surrender ceremonies on the battleship USS Missouri, officially ending World War II.
He entered the reserves on November 30.

After the war, he was arrested by the SCAP authorities and tried as a war criminal at the International Military Tribunal for the Far East in Tokyo.
He was found guilty of Counts 1, 27, 29, 31 and 32 of waging a war of aggression and sentenced to life imprisonment on November 12, 1948.

While in Sugamo Prison, he became a convert to Christianity.
Umezu died from rectal cancer in 1949 while still incarcerated.
Umezu returned to China in May 1938 as commander-in-chief of the IJA 1st Army. By this time, the IJA 1st Army had completed its combat operations, and was serving as a garrison force in Japanese-occupied northern China. From September 1939 he was commander-in-chief of the Kwangtung Army, which was likewise acting as a garrison force in Manchukuo. He was promoted to full general on August 1, 1940. 
In July 1944, Umezu was appointed as the final Chief of the Imperial Japanese Army General Staff, and a member of the Supreme War Council, following the resignation of Hideko Tojo. Along with Army Minister Korechika Anami and Chief of Imperial Japanese Navy General Staff,  Soemu Toyoda, Umezu opposed surrender in August 1945; he believed that the military should fight on, forcing the Allies to sustain such heavy losses in an invasion of Japan, that Japan could negotiate for peace under better terms. He was aware of the planned coup d'état by junior officers opposed to the surrender, but did nothing to either aid or hinder it. He was personally ordered by Emperor Hirohito to sign the instrument of surrender on behalf of the armed forces on September 2, 1945 and was thus the Army's senior representative during the surrender ceremonies on the battleship USS Missouri, officially ending World War II. He entered the reserves on November 30.
After the war, he was arrested by the SCAP authorities and tried as a war criminal at the International Military Tribunal for the Far East in Tokyo. He was found guilty of Counts 1, 27, 29, 31 and 32 of waging a war of aggression and sentenced to life imprisonment on November 12, 1948. 
While in Sugamo Prison, he became a convert to Christianity. Umezu died from rectal cancer in 1949 while still incarcerated.
Yoshijirō Umezu