What remnants of WWI lasted until 1919?

As far as Germany is concerned, there were “Freikorps” (free corps), volunteer military units, that fought against Soviet troops in the Baltics in 1919 and against Polish insurgents in Silesia in 1920/21. They also played an important part in the civil unrest in Germany in from 1918 - 1920 which was to some degree a civil war.

Some Freikorps were more or less officially recognized and even endorsed by the new German government and were later integrated into the new German military while others could be described as bands of thugs.

However, it would be inaccurate to describe these conflicts as a part of WW I.

I have always understood the fighting in what became the Soviet Union is regarded as being part of WW1. Maybe not typically, but there is a lot that is “untypically” known about WW1. Such as there being an Armistice and not a surrender. (Mentioned above).

This may have been what the book I’m reading (mentioned in the OP) was referring to… it’s in a chapter on New Guinea.

Also in June 1919 German airmen ‘scuttled’ a large part of their airship fleet rather than surrender it to the Allies as the Versailles Treaty would have demanded they do…

Are you certain of this? The german High seas Fleet was scuttled at Scapa Flow in 1919, but I have never heard of any airfleet being “scuttled”. How do you scuttle an airplane?

The Fokker D VII’s from memory had to be handed over but I have not heard of them being destroyed.

Reasonably sure; I found out about it a few years ago and I’m sure I have mentions of it in at least one book I have, but when I was about to post here I checked on-line and found this page. (para 3)
It does say it was inspired by the Grand Fleet’s action.
And they were airships, not planes, so I assume they ‘scuttled’ them by destroying the gasbags.

Wiki also mentions it in their ‘airship’ article

Or sending someone over to have a smoke in the hangars.

I understand that every iota of German military might had to be accounted for, but it’s hard to think of an airship as a “spoil” of war in the same way the German fleet was.

German airships most certainly were considered spoils of war. The British R-38 (ZR-2) was sold to the U.S. Navy because one of the German airships that should’ve been handed over was destroyed in its hangar by its crew. The French airship Dixmude was the ex-LZ 114, part of Germany’s war reparations, as was the Zeppelin-built ZR-3 U.S.S. Los Angeles.

Bri2k

One of the biggest ongoing events was the allied blockade of Germany. This did not stop with the armistice in 1918. The allied concern was that if they lifted the blockade during the armistice, Germany would be able to stock up on supplies and might restart the fighting. So the blockade was maintained for another eight months until the treaty was signed.

Scuttling an airship.

Apparently on 23rd June 1919, 2 days after the Grand Fleet scuttling, the airship crews hoisted the Imperial German Navy war ensigns on each airshiip, pulled away the ground supports and loosened the suspension tackles holding the zeppelins from the hanger roofs. The gas cells were no longer inflated and the 6 foot fall wrecked the metal framework and rendered the craft irreparable.

Summarised from Airshipwreck (1978) by Len Deighton & Arnold Schwartzman. It’s a book detailing the fates of all the airships which met with a sorry end from 1897 until the Graf Zeppeilin in 1940. Great little book.
Yes, that Len Deighton.