Commissioned at Saint John on 30 August 1969, she was selected to carry Governor General Roland Michener on a visit to the Netherlands and Belgium in 1971. On this trip she twice hosted royalty, on 16 April Queen Juliana and Prince Bernhard of the Netherlands, and the 22nd, King Baudouin and Queen Fabiola of Belgium. That June she carried out the first-ever replenishment of a hydrofoil at sea, the recipient being HMCS Bras d'Or. In 1974-75 Preserver served as supply ships for Canadian troops stations in Cyprus as part of a UN peacekeeping force. Throughout the Cold War, she and Protecteur engaged in all major NATO exercises, and have remained indispensable. On 7 April 1993, she returned to Halifax from duty off Somalia. Between 18 October and 23 November she served in Operation Forward Action (UN sanctions against Haiti). Preserver next departed on 27 January 1994, to join the multinational force carrying out sanctions against the former Yugoslavia. She operated there again from May to June 1995. She was one of the fleet units that assisted in the Swiss Air disaster off Nova Scotia in September 1998. She departed Halifax on 17 October 2001, with Charlottetown and Iroquois, to support Operation Enduring Freedom, the U.S.-led response to the terrorist destruction of the Twin Trade Towers, new York City, on September 11. She returned to Halifax on 27 April 2002.