Prince Ships
 

Prior to WWII, the Prince David, Prince Henry, and Prince Robert were luxury liners ordered by the Canadian National Railway. When Canada officially declared war against Germany in September 1939, the RCN quickly converted them to Armed Merchant Cruisers.

At a Halifax shipyard, all three underwent extensive alterations; the top two decks were cut away and light superstructures were fitted, eliminating the luxury cabins and lounges. Their hulls also had to be made more watertight after weakening over time to protect from potential torpedoes. They were also fitted with both anti-aircraft and anti-submarine weapons, although they did not have anti-submarine detection equipment.

HMCS Prince David
HMCS Prince Henry
HMCS Prince Robert 

Reference Links:
Government of Canada - Prince Ships Book