Around the outbreak of World War I in 1914 it was noted that the rapid development of dreadnought battleships might soon render US coast defenses obsolescent.

The United States Army's initial response was to place some existing 12-inch guns on high-angle long-range mountings.

[4] This weapon combined a large shell with a high trajectory, dropping almost straight down onto enemy trenches and fortifications.

The Coast Artillery wanted to use this capability for plunging fire against the thin deck armor of enemy ships.

Initially a single developmental 16-inch howitzer M1918, 18 calibers long, was produced and mounted on a railway carriage.

[7] Their mountings were open, making them vulnerable to air attack, a possibility the Army did little to allow for until the late 1930s.