But it was the captain's fractured domestic life - and his predilection for amorous experiences away from the hearth - which landed him before a court martial.

The 48- year old RAN veteran sat stony-faced in the unprepossessing surrounds of a nondescript building in Canberra's light industrial district of Fyshwick as he listened to 19 charges read out against him on Wednesday, including six of obtaining financial advantage by deception.

It is a case that goes to the heart of what it means to be married, at least in the eyes of the defence forces.

King is charged with fraudulently claiming up to $38,000 in living-away-from-home allowances.

The prosecution says he was not entitled to the allowances - paid to him for about 18 months from January 2010 when he was posted from Canberra to HMAS Albatross in Nowra as commanding officer - because he was no longer sexually or emotionally attached to his wife, fellow RAN captain Jacqueline.

In order to demonstrate that the marriage had disintegrated, Australia's military prosecutor, Lyn McDade, has submitted hundreds of emails that lay out, in often painful detail, King's blossoming relationship with a married Sydney woman named Robina Frew.

The emails are heavily redacted - probably for concerns of decency - and include his deeply disparaging descriptions of his wife's physique and his gushing enthusiasm for his lover. They include poems he wrote to Frew and a YouTube link to a song he said summed up their love.

The prosecution also produced a court affidavit that King submitted in May 2011, stating that he and his wife had separated on April 27, 2010. (To be divorced, a couple in Australia must have been separated for at least 12 months.)

But the most explosive evidence has been King's email correspondence, not just with Frew but with a woman with whom he had an affair in Britain while on a defence posting between 2003 and 2006.

King poured out his heart to the woman he dubbed his ''English Rose''about the vicissitudes of his relationship with Frew, who was wrestling with her guilt over hurting her own husband and King's wife.

For prosecutor Brigadier McDade, Director of Military Prosecutions, it is all a far cry from the controversy she weathered when two Australian commandos were charged in 2010 with manslaughter over the deaths of six civilians in a raid in Afghanistan (the charges were eventually dropped).

Defending King, who has pleaded not guilty, is Sandy Street, one of Sydney's top silks and a commander in the navy reserves.

Three weeks have been set down for the case, and from the tenor of jousting between McDade and Street, all three could be required.

One of King's mistakes appears to have been using his work email account for his romantic correspondence, as the contents of that account remain the property of the Defence Department.

In his initial interview with investigators in September 2011, played to the court yesterday, King insisted he was still married to his wife and helped maintain their shared home in Canberra.

He told them that what was in his heart was his own business, but he also stated emphatically that ''there is nobody else in my life''.

The allowances he claimed include rent and food assistance and reunion travel money - up to six trips a year. The allowances are there, McDade told the court this week, to compensate navy members who are separated from dependents, including spouses, because of their work.

But she says King did not meet this criterion when he left the couple's home in Canberra for Nowra in early 2010 because he would have separated from his wife Jacqueline anyway. ''There was going to be no living normally together; he was not going to live with her at all,'' she said. ''There was really no relationship any more with Mrs King.''

King's case is unusual because generally in other Australian courts martial where sexual conduct has been an issue there has been harassment or inappropriate behaviour alleged between the parties.

There is no suggestion of that here. The only reason King's dalliances are being held up for public scrutiny is because of what the prosecution claims they demonstrate about the bona fides - or lack of it - in his marriage.

In any other circumstances, his extra-marital dalliances would have been his own business.

In this respect, says former Chief of the Defence Force and former Admiral, Chris Barrie, Australia's military authorities are far less prurient than their US counterparts.

''We are not like the Americans,'' insists Barrie.

'I don't think we have a sanctimonious view of these things.

''An adultery ban is not written into the codes here.

''Frankly, provided the relationship is not an issue in the workplace, that is, involving harassment or conflict of interest in reporting, or anything like that, it's actually none of our business.''

By contrast, the US Uniform Code of Military Justice and its accompanying manuals plainly render adultery a military offence, though prosecutors still have to show that the conduct undermines ''good order and discipline'' or brings discredit on the armed forces.

This formal prohibition, and the cultural and religious peculiarities of the US, breed much greater moral condemnation of those in senior military ranks caught straying from the marital bed, as was evident when former CIA chief and former commander of US forces in Iraq and Afghanistan, General David Petraeus, was outed for an affair with his younger and also-married biographer, Paula Broadwell.

When the liaison became public, Petraeus's fate - instant resignation or dismissal - was inevitable.

The fact that the former military hero had left the army and become a civilian when Barack Obama made him CIA chief the previous year was no protection.

According to The Washington Post, Petraeus remained under the jurisdiction of the military code because of his collecting a military pension.

Petraeus's abject humiliation, endured after an otherwise exemplary four decades in the armed forces, has prompted an agonised debate in military blogs and the opinion pages of major US newspapers about the price he has paid for a short-term, mutually consenting affair with a fellow adult.

While many felt the affair and its consequences overblown, one military spouse and author, Jacey Eckhart, spoke for a widely-prevailing contrary view when she argued that she couldn't bear ''all of the shrugging off of fidelity … [ as if] we should expect a little cheatage [sic] to come our way simply because we spend too much time apart.''

And fellow military wife Alison Buckholtz of Slate acknowledged that the Petraeus headlines had prompted a ''quiet discussion in military-spouse circles about whether or not infidelity is a hazard of military life'' given regular separations, long hours and the opportunities for cheating.

It's a sensitive topic which gets far less open discussion here, perhaps because the consequences of straying outside marriage are not (King's case aside) usually so dire.

The Australian Defence Force's Instructions General explicitly state that relationships are a ''natural result of human interaction and as such may not be inappropriate or constitute a reason for sanction.''

But the rules also make clear that they may not be made manifest in the defence workplace ''where a superior and subordinate command or management relationship exists'' whether on a ship, a defence base, or in an office, and that liaisons must be reported where they might affect the chain of command.

Barrie recalls going through the debate about how far military authorities should take an interest in private sexual liaisons when he was leading the push, as defence chief, to get more women to sea in the mid 1990s.

''I used to have people say to me, 'this officer can't live with that officer or vice versa'.

''The answer was, 'get over it, its none of our business, provided these two people conduct themselves properly in the workplace'. ''

But he did institute a rule that ''in any relationship where two ranks are different, it is the responsibility of the senior person to report the relationship so that if there is a conflict of interest, such as one reporting on the other in the command chain, then something can be done about it. That was the rule.

''It recognised that these relationships would come to exist, it recognised that it was not appropriate to have someone in a relationship making a report on somebody else, and it was for management to deal with.''

Whatever the finding of the court martial, King will already have paid a high price for his actions.

Many in the military will be aghast at the extent to which his private communications with his lovers have been pulled apart, forensically examined and publicly exposed.

Many will also be wondering if they have strayed some way down the same path, claiming allowances for absence from home and hearth, while taking solace in the company of someone other than their official partner during a long posting.

We are yet to hear King's defence, but there will be serving ADF members examining their own affairs, and what the implications might be.