turret contributed to the secondary battery of sub-calibre weapons. In large armoured cruisers, wing turrets contributed to the main battery, although the casemate mounting was more common. At the time, large numbers of smaller calibre guns contributing to the broadside were thought to be of great value in demolishing a ship's upperworks and secondary armaments, as distances of battle were limited by fire control and weapon performance. In the early 1900s, weapon performance, armour quality and vessel speeds generally increased along with the distances of engagement; the utility of large secondary batteries reducing as a consequence, and in addition at extreme range it was impossible to see the fall of lesser weapons and so correct the aim. Therefore, most early dreadnought battleships featured "all big gun" armaments of identical calibre, typically 11 or 12 inches, some of which were mounted in wing turrets. This arrangement was not satisfactory, however, as the wing turrets not only had a reduced fire arc for broadsides, but also because the weight of the guns put great strain on the hull and it was increasingly difficult to properly armour them. Larger and later dreadnought battleships carried superimposed or superfiring turrets (i.e. one turret mounted higher than and firing over those in front of and below it). This allowed all turrets to train on either beam, and increased the weight of fire forward and aft. The superfiring or superimposed arrangement had not been proven until after South Carolina went to sea, and it was initially feared that the weakness of the previous ship's stacked turrets would repeat itself. Larger and later guns (such as the US Navy's ultimate big gun design, the 16"/50 Mark 7) also could not be shipped in wing turrets, as the strain on the hull would have been too great. Modern turrets Many modern surface warships have mountings for large calibre guns, although the calibres are now generally between . The gunhouses are often just weatherproof covers for the gun mounting equipment and are made of light un-armoured materials such as glass-reinforced plastic. Modern turrets are often automatic in their operation, with no humans working inside them and only a small team passing fixed ammunition into the feed system. Smaller calibre weapons often operate on the autocannon principle, and indeed may not even be turrets at all; they may just be bolted directly to the deck. Turret identification On board warships, each