Did this alleged military incident actually occur?

Another key point in Catton’s narrative is that the Union armies had seen a consolidation of commands that impacted unit identity and cohesion, then the terrain that was being fought over by it’s nature, rendered organized advances (or retreat) impossible. The end result was that eventually, individual soldiers were fighting individually not part of a traditionally coherent and organized group - the loss of officers in the field added to the effect.

Piling on to criticize the account quoted by the OP:

Flamethrowers? Flamethrowers were very specialized weapons for attacking fortified concrete bunkers and the like. There’s no reason to (and a lot of reasons not to) bring a flamethrower to a ‘fairly low and anonymous piece of ground’. If anything remotely like this happened, either the flamethrowers were complete BS added at some point because it made things sound even more horrible, or this is some very very distorted account of fighting in Stalingrad (which I understand did get very brutal at times).

C.L. Sulzberger on Stalingrad: "The fightiing within Stalingrad was a fantastic kind of warfare, waged inside cellars, in sewers, in blasted factories, behind the walls of demolished buildings. Every inch of the city was contested building by building, floor by floor, room by room, often in hand-to-hand combat. Quarter was seldom asked or given, and in this savage battle surrounded units commonly fought on until annihilated.

Were the Germans even in Finland in 1943? I thought the Continuation Warwas pretty much Finland v USSR until mid 1944.

The story sounds like a distorted account of the fighting on the Mamayev Kurganin Stalingrad. The date (‘Summer of 1943’) sort of fits (Mid September 1943), the fighting was certainly intense, but the two units virtually wiped out and the lurid details don’t fit.

Yes, they were in Finland from the start of Barbarossa, major operations were failed attempts to cut off Murmansk. A couple interesting related events, Germany was able to get Sweden to allow the rail transit of soldiersthrough Swedish territory from Norway, which was a violation of her neutrality. After Finland capitulated to the Soviet Union again in 1944, one of the provisions was for Finland to forcibly eject German forces still on Finnish soil. This led to the Lapland War between former allies Finland and Germany. Initially there was an agreement between the Finns and the Germans whereby the Germans conducted a scheduled phased withdrawal and the Finns would shell and then attack the now vacant former German positions. The Soviets caught on to what was happening and the Finns then had to engage in actual combat with the Germans. German actions in the now real retreat caused a great deal of resentment; they conducted extensive scorched earth as they retreated.

Thanks for the answers everyone, it was an account that stuck in my memory which is why I was wondering as to the accuracy of it.

If you can find the opening to Cold Mountain, where they show the Battle of the Crater, you can see how savage the Civil War became.