Les, it would be ludicrous to expect submarines to abide by a law that states that "warships should make adequate provision for the crews of merchant ships before they sank them". It's simply not feasible to do that and fight a submarine war in any effective manner.

It was clearly a law written without submarines in mind. It was written for surface ships. The person who wrote it probably didn't think submarines would count for much in war.

For the Germans NOT to eventually break such a law would have been inconceivable, given the realities of submarine warfare that they faced.

The USA in WWII sank so many Japanese merchant ships with their own version of unrestricted submarine warfare that they began to run out of targets by early 1945, and you know what they did then? They took to sinking the smallest fishing boats, sampans, anything Japanese they could find on the water, and machine gunning the civilian survivors of those boats in the water...and they were quite proud of themselves for so doing. This considerably exceeds the brutality of most German sub crews in either WWI or WWII, and it is also against international law. No one was tried for doing it.

The Japanese did similarly brutal things too, I might add, and they WERE tried for doing them. That part is well known, because they lost. The American atrocities are not so well known.

As you say, war is bad enough. It is unfortunate that there are plenty of ruthless (and frightened) people on both sides of most wars who are willing to make it a lot worse.