Dreyer's shell trials and the eighteen-month development cycle

Jellicoe had tried to improve shell quality as Director of Naval Ordnance and again as Third Sea Lord. After Jutland, he put Frederic Dreyer in charge of ordnance to accelerate the work. Trial-shell orders followed by May 1917, and revised fillings and test standards were introduced that September. The new 15-inch standard required penetration of a 10-inch plate at 20 degrees, while the 12-inch standard used a 6-inch plate at the same angle. That smaller target had defeated 15-inch shells during testing in March 1917. Mass production began in December, but the ammunition did not reach the fleet until April 1918, giving the counterfactual an approximately eighteen-month development and delivery requirement.