The Russo-Japanese War began on 8 February 1904, and on 18 June 1904 the Imperial Russian Army began the formation of the 6th Siberian Army Corps, consisting of the 55th and 72nd Infantry Divisions. On 27 July 1904, Radkevich's 10th Artillery Brigade became part of the new corps. The corps completed its formation in July 1904, and in September 1904 it became part of the 1st Manchurian Army. He saw action with the 10th Artillery Brigade in the Battle of Shaho in October 1904. On 11 December 1904, he became chief of artillery of the 6th Siberian Army Corps, and in that position participated in the Battle of Sandepu in January 1905. On 4 February 1905 he became provisional commander of the 72nd Infantry Division, leading it in the Battle of Mukden in February–March 1905. Official approval of his command of the division was promulgated on 27 May 1905. For his Russo-Japanese War service he was awarded the Order of Saint Stanislaus First Class with Swords, the Order of Saint Anna First Class with Swords, and the Golden Weapon for Bravery.