My father, the silent captain of the Cold War, proved how vital our nuclear submarines were and are

If you choose this career path and seek to command your own submarine, the selection course – aptly named “the Perisher” – is brutal and has as high a failure rate as any defence course outside of special forces. Unlike most courses with high failure rates, this doesn’t happen early in your career: you have to devote a significant portion of your life to submarines before you can even try them. Perisher is also cited as a major reason why our submarines have excelled over the decades. The number of countries that send their best officers to it, including the US, is a quantifiable endorsement.

To pass the Périssoir, as my father told me:

“The ‘professor’ had to be convinced that one could take a quick look through a periscope and mentally calculate whether any of the five warships bearing down on us were likely to hit us before one could complete evasive action by descending deep enough for them to pass safely over. One then had to decide when it was safe to return to periscope depth, based solely on the direction and movement of the noises emitted by their propellers. One had to take into account that in the time it took the submarine to go from safe depth to periscope depth, and vice versa if one had made a mistake, a ship at 30 knots could travel 2,000 yards.

“This is a simplistic description of a four-month course, half of which was spent on a simulator and half at sea in the Firth of Clyde. During the last month you were often deliberately deprived of sleep. Only by possessing a natural ‘periscope eye’ and a special kind of mental agility could you prove yourself safe at the controls of a submerged submarine surrounded by ships. You either could do it or you couldn’t, and it is not surprising that about one in three failed. On one occasion the whole six-year course failed.

Submariners of this era were not only learning to use this revolutionary new technology that was “as similar to conventional submarines as Dreadnought battleships were to sailing ships of the line,” they were doing it during the war.

And don’t worry, that’s how they saw it.

“We had to demonstrate that we could prevent the Soviets from penetrating the Atlantic from their bases in the Northern Fleet. Could we and our allies have stopped them? Answer: probably not… but at least we would have put a bloodbath on them and, at a higher level, they would know it.”

Acoustically, Russian submarines were “noisy” compared to ours and those of the US Navy. It wasn’t until the 1980s, when American sailors John Walker and Jerry Whitworth leaked decades of secrets to the Soviets, that the gap was closed.

This is not to say that detecting them was easy, even back then. As my father explained in “The Silent Deep” by Peter Hennessy and James Jinks, “making reliable estimates of a target’s trajectory, speed and range using simple passive sonars (only at listening) was one of the submariner’s most important and obscure black arts. A simple analogy is that it’s like being in a field with a herd of cows in complete darkness. One can hear munching, tail swishing, footsteps and the occasional seismic contribution to global warming, but only a fool would claim to know the exact position and expected movement of any animal. A bit of genius or a pure scam? The answer is a bit of both.”

This combination of art and science is the first reason I believe the roles played by an SSN will be the last of all maritime domains to be entirely replaced by an unmanned alternative. If air warfare is like rapid chess – quick and complex but ultimately formulaic (and therefore suitable for computational augmentation and/or fully unmanned operations) – underwater warfare is like the board game Diplomacy, whose Human nuances mean that even the most advanced AI can still be beaten.