October
Planning For Austrian AO
The 1st Army never demobilized. It was kept ready to march from its camps in Banat-north of Belgrade. It was considered a possibility that Prussia would feel emboldened by some new event and attempt an invasion of the Ottoman homelands. It was already planned to intercept its advance in Austria-no need to despoil the Ottoman countryside with war.
The Russian DoW on the O.E. was the event to embolden Prussia. Not content to just advance through Austria-it declared war on Austria also. No doubt the Prussian King believed his forces could reach the Austrian capital before Ottoman forces would arrive. I assume it was believed that Austria could be forced to surrender-or be marginalized quickly then followed by a joint invasion of the O.E. A very bold plan indeed.
The reaction was swift. The trail to Vienna is one which the Otto 1st Army has become very familiar with in past years. The correct path was known-and taken. A battle was expected either in Pressburg or Vienna itself. Moravia is the natural approach to Vienna from the north-and the Prussian Armies were just north of Moravia. A junior officer could have deduced the proper course of action.
This map shows the target locations of the Ottoman forces-other nations are shown in their last known positions.

Banking establishments are more dangerous than standing armies.
Thomas Jefferson