During the surprise Japanese torpedo boat attack on Port Arthur, starting the Russo-Japanese War, "Tsesarevich" was hit by a Japanese torpedo but remained afloat and contributed to driving off the Japanese attack. Grigorovich was awarded the Order of St Vladimir, 3rd class with swords for his role in the battle. After the death of Admiral Stepan Makarov, he was promoted to rear admiral and appointed chief of Port Arthur's port. Under his effective management, Russian Pacific squadron had no shortage of coal, munitions or any supplies during the Siege of Port Arthur. In 1904 he was also awarded with the Order of Saint Stanislaus, 1st class.