As in WW1, the Royal Navy again in WW2, to augment its Naval ships made use of selected Merchant ships by converting them to Armed Merchant Cruisers. These vessels ranged from 6,000 to 22,000 tons, and were fitted out, usually with old WW1 type 6 inch guns, complemented with a meagre and totally inadequate Anti-aircraft armament. Given the title of His Majesty's Ship, and a White Ensign to fly these ships were in general, used for convoy escort work, and proved to be no match for any encounter with modern German capital ships. Read more about Allied Armed Merchant Cruisers of WW2
Warships and submarines of the Royal Navy.