Intended as a shore bombardment vessel,
M20s primary armament was a single
9.2 inch Mk VI gun removed from the
HMS Gibraltar. In addition to her 9.2-inch gun she also possessed one
12 pounder and one
six-pound anti-aircraft gun. She was equipped with a four-shaft Bolinder two-cylinder semi-diesel engine with 640 horsepower that allowed a top speed of eleven knots. The monitor's crew consisted of sixty-nine officers and men. ==Construction==