War-time Reorganization
On September 15, 1939, the Riverine Flotilla received orders from the commanding officer of the Independent Operational Group Polesie, Gen. Franciszek Kleeberg. Because of a possible breakthrough of the German forces in the northern sector of the front, the orders for the Flotilla were to prepare a defence of a 200 kilometres long front along the Prypeć river. The forces were to be divided into 8 semi-independent task forces, each defending a separate part of the river. However, a particularly dry and sunny summer resulted in shallow waters preventing many ships from reaching their area of operations. In addition, the Soviet invasion of September 17, 1939 made the plans obsolete.
Read more about this topic: Order Of Battle Of The Riverine Flotilla Of The Polish Navy