At this early stage of the Second Great War the mass armies of the belligerents were still being assembled. Fighting, if it were to occur at all, would need to be done by those units that were fully capable during peacetime. The river gunboats of the Danubian countries had been at full strength in peacetime and it was expected that, as in the First Great War, these units would be amongst the first to fight. Ritter von Trapp, however, concentrated his units at Novi Sad and awaited events. He had seen first-hand the economic tentacles that tied Serbia and Romania to Austria-Hungary and would not fire the first shot, hoping that these countries' self-interest would win out against martial escapades.

The concept of foreign observers remained in use. Thus we find a Sub-Lieutenant from Britain's Royal Navy (who at this point in the Second Great War remained non-aligned) assigned to Ritter von Trapp's command. In the best tradition of the Royal Navy the sub-lieutenant had urged Trapp to attack Belgrade before the Serbs could mobilize. The Englishman, whose name time and triviality have obscured, had a casual habit of leaving his notes out for view, counting on the lack of a local translator for security. Ritter von Trapp, however, knew enough English to translate most of the note. He bristled at some of the comments that the sub-lieutenant had made but one struck him as odd. It was only after the war that he realized that the comment "lack of hart" was a misspelling and not an admonition to hunt.

Spurred by the apparent admonition to correct his "lack of hart" Ritter von Trapp took the two largest and strongest units of the flotilla "hunting" to see if he couldn't start the process of clearing the Danube banks of shore-based batteries protecting Belgrade. The Serbs had expected some flotilla action and had moved these guns across the Sava 15 miles to the north to provide some resistance to the river-borne artillery that had ravaged Belgrade at the beginning of the First Great War. At Belegis in southern Hungary an island created the possibility of grounding some of the larger units of the flotilla as well as channelizing any river traffic, and wooded banks provided the possibility of giving some cover to the Serbian guns. Ultimately the Serbian guns were removed by two platoons of Marines and two small mine-laying boats working in tandem, causing one wag in the headquarters at the Petrovaradin Fortress in Novi Sad to say that, "if Trapp was looking for a stag, he certainly found only a doe."

Counters and maps from River Fleets may be used to play Blue Danube scenarios.