During the ironclad age, the range of engagements increased; in the Sino-Japanese War of 1894–95 battles were fought at around 1 mile (1.5 km), while in the Battle of the Yellow Sea in 1904, the Russian and Japanese fleets fought at ranges of 3.5 miles (5.5 km). The increase in engagement range was due in part to the longer range of torpedoes, and in part to improved gunnery and fire control. In consequence, shipbuilders tended towards heavier secondary armament, of the same calibre that the "intermediate" battery had been; the Royal Navy's last pre-dreadnought class, the "Lord Nelson" class, carried ten 9.2-inch guns as secondary armament. Ships with a uniform, heavy secondary battery are often referred to as "semi-dreadnoughts".