I'm an American Seaman Second Class on a USN Cruiser during World War II. We dock at an Australian port and I get shore leave. I go on an epic bender and sober up two days later to find my ship has left port without me. How much trouble am I in, and what are my options?

Part I

On the bright side, you're in good (well, maybe not exactly morally) company. 16 million men served in World War II, and there were 2 million courts martial convened. There were probably tens of millions of non judicial punishments (NJP) below that - one particularly notable Navy miscreant went through 61 Masts along with his 9 court martials - but there's no way to really tell the actual totals of NJP handed out as the overwhelming majority of both crimes and punishments never made it to someone's personnel file (jacket).

Now the only good news for you is that despite The Articles for the Governance of the Navy aka Rocks and Shoals getting its memorable nickname from one of the 20 Hanging Offenses named in Article 4 ("The punishment of death or such other punishment as a court martial shall adjudge...may be visited on any person...[who] intentionally or willfully suffers any vessel of the Navy to be stranded, or run upon rocks or shoals, or improperly hazarded or maliciously or willfully injures any vessel of the Navy..."), Absent Over Leave isn't among the crimes that can get you charged with the death penalty.

In general, those are limited to actions that directly put ship and crew in mortal peril, be it insubordination, sleeping on watch, or behaving improperly while engaged with the enemy. A marvelous if fictional illustration of the last that's well worth reading is in the book version of the Caine Mutiny, when the mutineers' attorney presents a defense that his clients' actions were in direct response to Captain Queeg behaving with cowardice in the face of the enemy, which in Queeg's position as CO is particularly devastating as it constitutes four separate Article 4 offenses. The initial reaction of the court when he begins to do so is shock and a bit of outrage. That gets replaced when they all have the grim realization that not only do the mutineers have potential grounds for an acquittal but the court itself now is faced with a capital case against the authority that convened the whole mess in the first place - and that it's likely far stronger than the one argued against the mutineers.

But you still made the bad mistake of being Absent Over Leave (AOL), tripping Number 19 ("Or is absent from his station or duty without leave or after his leave has expired") of the 22 Article 8 offenses that require court martial, like when one runs their ship upon rocks and shoals through inattention or negligence instead of intentionally. In and of itself, that's not terrible. If you commit a potential capital offense under Article 4, the Navy must try you in front of a general court martial - the highest level available - because only that panel has the authority to decide whether to impose the death penalty.

Article 8, though? You'll usually end up with a summary (3 man) or special (1 man) court martial. This is generally to your significant benefit since the lower the level of the court martial, the lower the punishment it can impose. Instead the potential of life in prison or forfeiting your pay for the rest of your career, the more junior court martials have significant caps on the severity of punishments available - like a maximum of one year in the brig and 6 months of pay being forfeited. Unfortunately, since it's a named Article 8 offense, the option of Mast isn't available, where the maximum punishment drops to around the 60 day range and in lieu of that often included a couple weeks of the legendary bread and water diet, which remarkably took until the 2010s to be eliminated.

Here's the even greater upside of less serious charges: if you can present a good defense you might even have a shot of walking away scot-free. In fact, while CO of Lexington in the early 30s, one then-Captain Ernest King was outraged to discover that a cook who had been a day late reporting back from home leave had run afoul of a local sheriff. That sheriff knew if he'd detained the sailor he had the poor guy in between a rock and a hard place: either he'd have to pay a bribe for release or likely lose at least a month's pay when getting back to the ship late. King intervened in the court martial and released the cook without punishment, turned the tables, and called in several Federal agencies to prosecute the sheriff.

So in general - both back then and today - you're usually going to want to be brought before the lowest level hearing that's available. Except what you (and 75% of the others who went AOL/AWOL at the time, with 84% admitting later they'd have never done so had they known) probably weren't aware of is that if your AOL took place and caused you to miss your ship...the Navy automatically escalated that straight back up to a general court martial.

Oops.

(Edit: added special court martials, which despite one source claiming otherwise did apparently exist pre-UCMJ per the Manual of Courts Martial 1921. Edit 2: Article 8, not Article 4, and cleaned up the junior court martial section.)