After the preceding Iron Duke class had turned out well, the Royal Navy decided to move on to a ship armed with 15" guns, and the ships of the 1912 construction programme were designed to bear that new weapon. This was quite a risk, as the gun had not yet been developed, but all went well in the end as the 15" gun turned out to be a full success. The new ships were initially intended to bear five twin turrets like their predecessors, but it was found that eliminating the central turret would allow a much bigger power plant and a greatly increased speed. To allow for a top speed of 25 knots, it would require an all oil-fired power plant, and so the Queen Elizabeth class became the first batch of capital ships fuelled solely by oil.