A lone Canadian submarine masterfully exploited ocean acoustics and stealth to achieve a simulated "kill" against a U.S. Navy carrier strike group.
By Kris Osborn, Warrior
During a NATO exercise in the 1980s, a Canadian Oberon-class diesel-electric submarine penetrated the defenses of a U.S. carrier strike group centered on USS Dwight D. Eisenhower and achieved a simulated “kill”— without being detected.
A nuclear-powered aircraft carrier with an air wing supported by cruisers, destroyers, and attack submarines, was designed to operate in contested waters and defeat the Soviet submarine threat. Canada’s Oberon-class boats were diesel-electric submarines commissioned in the 1960s. The Oberon class was slower, and far less technologically sophisticated than its nuclear counterparts, yet it proved surprisingly decisive in critical wargames against a massive concentration of US Navy surface power.
Canadian Submarine Found “Quiet” Spaces
Nevertheless, an interesting essay in 1945 explained that Canada’s “battery powered” submarine was able to achieve this simulated kill by finding “quiet” spaces beneath the carrier where it was not detected. The Oberon’s crew, reportedly trained extensively in anti-submarine warfare from the defender’s perspective, understood how to use these features to their advantage, positioning the boat where it was least likely to be heard.
The Oberon was stealthy. When running on batteries rather than diesel engines, a diesel-electric submarine is extraordinarily quiet—often quieter than the ambient ocean noise. Nuclear submarines, though fast and capable of remaining submerged indefinitely, must continuously run reactors and coolant pumps, creating a persistent acoustic signature. In an exercise setting that emphasized realism, the Canadian boat exploited this advantage by remaining slow, patient, and silent, blending into the acoustic background rather than racing to intercept the carrier. This enabled the Oberon to successfully find a quiet space within range from which to launch a simulated torpedo attack to sink the carrier.
“Using the natural acoustic conditions of the ocean and its own quiet propulsion system, the submarine slipped past the outer defenses of the carrier group. It evaded sonar-equipped destroyers and surveillance aircraft, exploiting gaps in coverage and limitations imposed by the exercise’s rules of engagement.
Oberon Torpedo Attack
At the critical moment, the submarine simulated a torpedo launch. The exercise umpire, a U.S. Navy officer tasked with adjudicating the scenario, evaluated the situation and declared the carrier “sunk,” the 1945 essay states.
During the Cold War, U.S. anti-submarine warfare focused heavily on countering fast, deep-diving Soviet nuclear submarines. Screening tactics, sonar settings, and patrol patterns reflected that expectation. A small, slow-moving diesel boat operating close to environmental limits did not align with the kinds of threats expected by the Pentagon at this time As a result, the carrier group’s sensors and operators had their sensors and detection technologies programmed to look for something “other” than the Oberon.
Oberon Inspires US Navy Subs?
This incident likely informed the US Navy’s development of attack submarines in subsequent decades, given the large extent to which Virginia-class submarines are built with specialized engine-quieting technologies. Virginia-class attack submarines have also greatly increased their surveillance capabilities as they can quietly conduct forward reconnaissance in high-threat areas without being easily detected. This rare but heavily influential simulation development in the 1980s may also have inspired or informed the Navy’s decision to build its new Columbia-class submarines with diesel electric propulsion. Much like the Oberon did with success in the simulation, Columbia submarines are engineered to quietly “linger” in undetected waters, often limiting movements to reduce detectability.
In the case of the Oberon, simulated exercises and wargames seemed to achieve their intended purpose, meaning they are designed to expose weaknesses and vulnerabilities in time to fix or correct them. The Eisenhower episode reinforced the continuing relevance of diesel-electric submarines, particularly in coastal and constrained waters, and underscored the danger of overconfidence. It also highlighted the importance of training against a wide spectrum of threats, not just the most technologically advanced ones.
Kris Osborn is the President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a highly qualified expert in the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University