In the several years that followed, he was assigned to serve at various times as commander of the Department of the Colorado, the Lakes, the East, and eventually the Pacific Division. When the Russo-Japanese War exploded in early 1904, eight American officers were promptly sent to the Manchurian front as observers. Chafing at the bit at his headquarters in Fort Mason, San Francisco, MacArthur requested that he also be assigned as a military observer upon hearing of the outbreak of war between Russia and Japan in 1904. He finally secured the appointment, but arrived in Manchuria in mid-March, 1905, just after the major fighting had ended with the Japanese triumph at the Battle of Mukden. When the Portsmouth Peace Conference was convened in August, MacArthur was sent to Tokyo as military attaché to the American legation.