[citation needed] At the end of January 1939, Lieutenant Colonel Kiyotake Yoshimaru took command of the regiment; Yoshimaru was promoted to full colonel in March, and under him the regiment participated in the Battles of Khalkhin Gol against the Soviet Union in 1939,[1]: 351 as part of the 1st Tank Corps.
At this time the 3rd Tank Regiment had the following order of battle:[1]: 349 Japanese armor fared poorly in these battles, the low-velocity guns being unable to penetrate Soviet armor, while being themselves vulnerable to Soviet high-velocity tank guns.
Colonel Yoshimaru himself was killed when his command tank was destroyed by Soviet gun fire on 3 July 1939.
During the action of 2 and 3 July, the 3rd Tank Regiment was badly mauled by the Soviet army forces.
[2] The 3rd Tank Regiment was detached from the 1st Armored Division and attached to 11th Army for Operation Ichi-Go against China in 1944.