Resolute.

This is coolbert:

“A Chinese [soldier] is tough, he is not afraid of anything. His brother may be killed in battle, but he will not bat an eye... If he understands that he faces an enemy, the enemy is not to be envied. A Chinese [soldier] will fight to the very last,” - - Soviet commander Yakir.

"Chinese soldiers were some of the most disciplined, resilient and cruel among those fighting in the Red Army in the Russian Civil War. They were practically never taken prisoner."

Ethnic Chinese in discrete fighting units a component of the Red Army during the Russian Revolutionary [Civil] War.

Noted for their resoluteness in combat. 

Recall the rating scheme of the famous/infamous Japanese senior officer Colonel Tsuji from the era of the Second World War.

With regard to "fighting spirit" Chinese rated as # 2. Exceeded only by the Japanese #1 best. "Fighting spirit" most likely best defined as doggedness and persistence, offense or defense.

The remainder of Colonel Tsuji's list [in descending order] to include # 3 Russians, # 4 Ghurkha, # 5 American, # 6 Australian, # 7 British Indian Army troops, # 8 English.

Many of these Soviet Red Army Chinese ethnics continuing their military service under the command of Mao. Valuable assets their skill and combat experience greatly appreciated:

"However, most of those who made up the Red Army’s Chinese contingent returned to their homeland. With a wealth of combat experience and additional specialized training, they went home to help Mao Zedong establish Soviet rule there and soon became the core of the Chinese Communist Party"

coolbert.