Near the end of the Second World War he commanded the 26th Tank Regiment during the Battle of Iwo Jima and was killed in action during the defense of the island.

His father had various high-level positions in the Ministry of Foreign Affairs and Imperial Privy Council, leading up to ambassador to China's Qing dynasty during the Boxer Rebellion.

There is speculation this was intentional and done for the benefit of host country Nazi Germany, with whom Japan would sign the 1940 Tripartite Pact, forming the Axis Powers.

On July 18, 1944, while en route from Pusan to Iwo Jima, the ship Nisshu Maru transporting the regiment was struck by torpedoes fired by submarine USS Cobia (SS-245).

After extensive air and naval gunfire bombardment, the United States Marine Corps launched an amphibious assault on Iwo Jima starting February 19.

The American intelligence officer responsible for this attempt was Sy Bartlett of the 315th Bomber Wing out of Guam, who would later write the novel and film screenplay Twelve O'Clock High (1949).

One theory is that he found himself in the midst of enemy forces on the morning of March 21 and was killed by machine gun fire while moving to the regimental headquarters.

Yet another is that he was burnt to death by American flamethrowers on March 22, or that he and several subordinates carried out a final assault and were killed in action.

John C. Shively, in his novel The Last Lieutenant (2006), recounts a story told by his uncle in which his platoon fires upon a group of Japanese soldiers during the night.

Nishi was posthumously promoted to the rank of colonel and awarded the Order of the Rising Sun, Third Class, Gold Rays with Neck Ribbon.

[1] In 2012 Yasunori Nishi was appointed vice-chairman of Iwo Jima Association of Japan and attended the 68th Reunion of Honor held on the island in 2013.

[8] Nishi's gold medal from the 1932 Los Angeles Olympics is on display at the Chichibunomiya Memorial Sports Museum in Funabashi.

[10] Uranus died one week after Nishi at the Tokyo Equestrian Park, he was later buried at the Army Cavalry School in Tsudanuma but the grave was destroyed in a US bombing raid.

[11] In the 2006 film Letters from Iwo Jima, Baron Nishi was played by Korean-Japanese actor Tsuyoshi Ihara.

An anecdote repeated by Kakehashi Kumiko in the February 2006 issue of Bungei Shunju magazine is that in the final days of the battle, as the number of commanding officers who refused to put their men in caves increased, Nishi agreed that they should go out and fight together.