Intended as a shore bombardment vessel, M15's primary armament was a single 9.2-inch Mk X gun which had been held as a spare for the Drake and Cressy-class cruisers.

She was equipped with triple expansion steam engines rated to 800 horsepower (600 kW) that allowed a top speed of 11 knots (20 km/h; 13 mph).

M15 was ordered in March 1915, as part of the War Emergency Programme of ship construction.

26 men lost their lives in the sinking of M15, one kilometre (0.62 mi) from shore, in 90 metres (300 ft) of water.

After more than a century at the bottom of the sea, while Israeli sources claim the material was found to be unusable Hamas published a video of their members using it to make rockets .