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

If you choose this career and want to command your own submarine, the selection course – aptly named “Perisher” – is brutal and its failure rate is as high as any other course in the defence field outside of special forces. Unlike most high-failure courses, this course is not at the start of your career: you have to spend a significant part of your life working with submarines before you even get a chance to try. Perisher is also cited as a key reason for the excellent performance of our submarines over decades. The number of countries that send their best officers there, including the US, is measurable validation.

To get past the Perisher, as my father told it:

“You had to convince the ‘teacher’ that you could take a quick look through a periscope and calculate in your head whether one of up to five warships charging at you would hit you before you could complete your evasive action by going deep enough to allow them to safely clear the surface. Then you had to decide when it was safe to return to periscope depth based on nothing more than the direction and movement of the noise their propellers made. You had to take into account the fact that a 30-knot ship could travel 2,000 yards in the time it took the submarine to get from safe depth to periscope depth and back again if you were wrong.

“This is a simplified description of a four-month course, half in a simulator and half at sea in the Firth of Clyde. During the final month, sleep was often deliberately deprived. Only with a natural ‘periscope eye’ and a special kind of mental agility could one prove that one could safely command a submerged submarine surrounded by ships. Either you could do it or you couldn’t, and not surprisingly, about one in three failed. In one case, the entire six-month course was failed.”

The submariners of this era not only learned to use this new and groundbreaking technology, which was “as similar to conventional submarines as dreadnought battleships were to sailing ships of the line,” but they did so in the midst of war.

And there is no doubt that they saw it that way.

“We had to prove that we could stop the Soviets from advancing into the Atlantic from their Northern Fleet bases. Could we and our allies have stopped them? Answer: probably not… but we would have at least given them a bloody nose and at a higher level they knew it.”

Acoustically, Russian submarines were “loud” compared to ours and those of the US Navy. It was not until the 1980s, when US sailors John Walker and Jerry Whitworth passed decades-old secrets to the Soviets, that this gap was closed.

But that doesn’t mean that even then, spotting them was easy. As my father explained in The Silent Deep by Peter Hennessy and James Jinks, “The submariner’s most important and mysterious black art was to make a useful estimate of a target’s course, speed and distance from passive (audible only) sonar bearings. A simple analogy is that it’s like being in a pasture with a herd of cows in pitch darkness. You hear chewing, tail wagging, footsteps and the occasional seismic impact on global warming, but only a fool would claim to know the precise PIM (position and intended movement) of any individual animal. Part genius or pure fraud? The answer is: a bit of both.”

This combination of art and science is the main reason I believe the duties of an SSN will be the last maritime domain to be completely replaced by an unmanned alternative. If air warfare is like speed chess – fast and complex, but ultimately formulaic (and thus amenable to computer augmentation and/or fully unmanned operations) – then submarine warfare is like the board game of diplomacy, whose human nuances mean that even the most advanced AIs can still be beaten.