A major upgrade programme in the 1990s overhauled them for area-wide anti-aircraft warfare with the installation of a vertical launch system for Standard SM-2MR Block IIIA missiles.

With the disbandment of Banshee fighter aircraft squadrons and the retirement of the Second World War-vintage destroyers in the early 1960s, the Royal Canadian Navy no longer had air cover nor fire support capabilities.

[3] However, due to rising costs and an ambitious Defence Minister, Paul Hellyer, who had his own ideas as to where the Royal Canadian Navy should spend its money, the GPF program was cancelled on 24 October 1963.

[4] After the cancellation of the GPF program, the Royal Canadian Navy continued to design a vessel able to fulfill the lost capabilities.

Several designs were drawn up, one of which was an improved version of the GPF with a better missile system, anti-submarine warfare (ASW) rocket and large calibre gun.

The Royal Canadian Navy submitted a design that matched what Hellyer required that used steam turbines instead of gas and had a planned cost of $35 million, similar to the most recent ships constructed based on the St. Laurent class.

[5] On 22 December 1964, Hellyer announced the planned construction of four new helicopter-carrying destroyer escorts as part of a larger package of procurement for the navy.

[12][13] With the arrival of the Iroquois-class destroyers, a special service centre was created ashore with the same computer system, which was far more advanced at the time compared to anything else in the navy.

Designed with enclosed citadel, bridge and machinery spaces,[15] the sources disagree about the general description of the Iroquois class.

In contrast, the Iroquois-class destroyers' much larger Sea Kings were able to carry a complete sensor suite and operate at much longer ranges independently of the launch ship.

[19] The Iroquois class was originally equipped with one OTO Melara 5-inch (127 mm)/54 calibre gun that was capable of firing 40 rounds per minute.

[21] Named the Tribal Refit and Update Modernisation Program (TRUMP), the design contract was awarded to Litton Systems Canada Ltd. and required a total reconstruction of the superstructure, new propulsion, weaponry and electronics.

[16] In addition to their conversion to AAW vessels, the Canadian Forces sought to improve their command, control and communications capabilities in order to make them task group leaders.

[16] The propulsion was overhauled also, with two GM Allison 570-KF cruising turbines being installed in place of the Pratt & Whitney FT12AH3 models which created 12,800 shaft horsepower (9,500 kW).

The OTO Melara 5-inch gun was removed and replaced by a 29-cell Mk 41 vertical launch system (VLS) for the SM-2 Block 2 surface-to-air missile.

[21] In 'B' position an OTO Melara 76 mm (3 in) Super Rapid gun was installed in the space vacated by the removal of the Sea Sparrow launchers.

After Operation Desert Storm began in January 1991, the task group undertook escort duties for hospital ships and other vulnerable naval vessels of the coalition.

When the Ticonderoga-class cruiser USS Princeton detonated two Iraqi bottom-moored influence mines (MANTAs) at the north end of the Persian Gulf and was seriously damaged, her commanding officer specifically requested the assistance of Athabaskan.

Athabaskan could simultaneously operate two CH-124 Sea King helicopters, originally for anti-submarine warfare, which proved useful in searching out mines for long periods until a U.S. Navy minesweeper arrived.

[31] On 3 August 2000, Athabaskan sent her helicopter to board GTS Katie, a cargo vessel carrying Canadian military equipment whose charterer refused to deliver them.

[40] In 2003, while readying for deployment to Operation Apollo, Iroquois's Sea King crashed on deck and the ship was forced to return to Halifax.

[42] In 2008 Iroquois was among the Canadian warships deployed to the waters off Somalia as part of CTF 150, the multi-national task force that concerned itself with drug and people smuggling and piracy in the region.

[45] Despite Huron being the most recently refitted Iroquois-class destroyer, she was placed in mothballed status in 2000, due to a personnel shortage following defence cutbacks during the late 1990s.

[48] In May 2014, while visiting Boston, Massachusetts, severe cracks were discovered in the hull of Iroquois requiring her immediate return to Canada and lay up for inspection.

[49] On 19 September 2014, the Royal Canadian Navy announced that these two ships were to be paid off along with the Protecteur class, leaving only Athabaskan active.

In October 2018, a group led by BAE Systems along with its partners Lockheed Martin Canada, CAE Inc., L3 Technologies, MacDonald, Dettwiler and Associates and Ultra Electronics, were selected as the preferred design.