Joining the war, USA headquarters knew that the Heavy Artillery on Railway Mount is an important weapon in the modern conflict. Therefore, the Naval Gun Factory proposed the existing naval tubes of 14 inches Mk IV/1 (50 calibres), and designed, together with the Baldwin Locomotive Works, an improvised railway (12 axles) to create the '14 inches Gun, Naval Railway Mount Mk I'. 11 such guns were build, but only 5 of them early enough to be used in France, manned by the US Navy.

This mount had the interesting particularity of offering a shield to its servants, as well as a complete barrack system in the wagons ! But, designed in the urgency, it demonstrated several design defects :difficult maintenance, need to build a specific firing position with a pit under the gun when firing at elevations over 15 degrees, and a huge weight, balanced unevenly on the axles.

Because of this latest point, the trip from the guns assembly in the Chantiers de la Loire in Saint Nazaire (France) to the front (Camp de Mailly) needed several days (at a maximum avergae speed of 5 miles/hour), at the price of important damages to the bearings and journals, and the reinforcement of several bridges on the French railways, including the heavy traffic ones.

They were dispersed in the surroundings of Rethondes, Verdun and Nancy to destroy the distant targets they were assigned. The very last shell was fired on November 11th 1918 at 10:57am, just 3 minutes before the cease-fire... The guns were repaired and disassembled in the Chantiers de la Gironde in Bordeaux (France) in January 1919 before their trip back to USA.

Main characteristics :

• Weight in firing position : 242676 kg
• Calibre : 355.6 mm
• Tube length : 50 calibres
• Projectile weight : 545 kg
• Initial speed : 853 m/s
• Maximum range : 38000 m
• Elevation range : 0 / +43 degrees
• Direction range : 5 degrees