In 1981, a Canadian Oberon-class submarine and worth about $80 million slipped past an entire US Navy carrier group and ‘sank’ one of the most capable American aircraft carriers in a NATO war game

In 1981, an aging Canadian diesel-electric submarine achieved something that sounds almost impossible. The submarine slipped through the defenses of a powerful US Navy carrier strike group and carried out a simulated torpedo attack on the USS Dwight D. Eisenhower, one of America's newest and most advanced aircraft carriers at the time.

The submarine was a British-built Oberon-class boat, lacking the advanced technology found aboard today's underwater vessels. Yet during a major NATO exercise, its ability to remain quiet and undetected allowed it to get close enough to the Nimitz-class supercarrier to score a simulated kill. A nuclear-powered Nimitz-class aircraft carrier costs roughly $5,500,000,000 in today’s money.

The encounter offered a striking reminder that when it comes to submarine warfare, age and technology do not always determine the winner.


ALSO READ: Mark Zuckerberg and Priscilla Chan gave $4 million to save a 600-year-old Hawaiian fishpond from development

The USS Eisenhower was one of the most powerful ships of its era

The USS Dwight D. Eisenhower (CVN-69) was among the newest and most capable American aircraft carriers when the 1981 NATO exercises took place. The carrier was part of major Cold War-era naval operations designed to test how Allied forces would respond to a potential conflict in the North Atlantic and Norwegian Sea.

The exercises involved American, British and Canadian forces, along with large numbers of aircraft and ships. During one phase, the carrier strike groups were expected to move through the North Atlantic and conduct simulated attacks against enemy positions.

ALSO READ: MacKenzie Scott has given away $26.4 billion since her divorce from Jeff Bezos

But the exercise produced an unexpected result. A Canadian Oberon-class submarine reportedly penetrated the escort screen without being detected and carried out a simulated torpedo attack against Eisenhower.

In the language of the exercise, the carrier had been “sunk.”

How an old submarine got close to a nuclear-powered carrier

The Oberon-class was hardly a modern technological marvel by today's standards. These submarines were conventionally powered, relying on diesel-electric propulsion rather than nuclear power. They also lacked the sophisticated air-independent propulsion systems found on some newer submarines.

Yet they had one major advantage: silence.

ALSO READ:Jacob Coxon quits Anthropic with chilling AI warning

The Oberon-class developed a reputation for being exceptionally quiet. That made the submarines difficult to detect, particularly in an era when anti-submarine warfare depended heavily on finding the faint acoustic signatures produced by underwater vessels.

Unlike a nuclear-powered submarine, a diesel-electric boat could also shut down its diesel engines and operate on battery power. That made it possible for the submarine to become extremely difficult to hear while approaching its target.

The Canadian submarine was not the only problem

The 1981 incident was not an isolated example of conventional submarines defeating much larger naval forces in exercises. Sweden's Gotland-class submarines later attracted significant attention during exercises with the US Navy.

The Swedish boats were able to exploit their quiet operation and air-independent propulsion to remain underwater for extended periods.

The Gotland class uses Stirling air-independent propulsion, allowing it to stay submerged much longer than traditional diesel-electric submarines that need to surface or snorkel more frequently to recharge their batteries.

During exercises, the Swedish submarine reportedly managed to penetrate defenses around the USS Ronald Reagan, another Nimitz-class aircraft carrier. These encounters were simulated, but they gave naval planners an important lesson.

Why submarines remain a threat to aircraft carriers

An aircraft carrier does not operate alone. A carrier strike group normally includes destroyers, cruisers, aircraft and other systems designed to detect and defeat enemy submarines.

That creates multiple layers of protection around the carrier. But underwater warfare is different from a conventional surface engagement. A submarine does not have to defeat an entire carrier strike group. It only needs to remain hidden long enough to reach a firing position.

That is why submarine detection remains one of the biggest challenges for carrier strike groups. A relatively inexpensive conventional submarine can potentially force an extremely expensive carrier and its escorts to spend enormous resources searching for it.

Old military technology can still surprise modern forces

The Canadian Oberon incident also highlights a broader lesson from military history. Older weapons are not automatically obsolete.

In Ukraine, for example, aging small arms and Cold War-era equipment have appeared alongside modern weapons. Russia has also turned to older armored vehicles stored for decades as battlefield losses have mounted.

Technology matters enormously in warfare, but so do tactics, geography, training and the ability to remain undetected. The Canadian submarine did not need futuristic weapons or advanced electronics to threaten one of the world's most powerful warships.