From 1900, Fok was commander of the 4th East Siberian Rifle Brigade, and participated in the suppression of the Boxer Rebellion.

[1] During the Russo-Japanese War, Fok commanded the 4th East Siberian Rifle Division stationed at Port Arthur.

He was noted for his precipitous retreat and failure to reinforce Colonel Nikolai Tretyakov at the Battle of Nanshan, leading directly to the Russian defeat.

As commander, Fok constantly refused to commit reserves or reinforcements to front-line units, and after eight months of the siege was one of the first to urge acceptance of the surrender terms extended by Japanese general Nogi Maresuke at the end of 1904.

Faced with strong public criticism, he was arrested and brought before a court martial in late 1906 on his return, but was acquitted and released from military service in 1908.