Northern Mazovia became operational area of the Army "Modlin". Its main task was to delay the movements of the enemy in the direction of East Prussia towards Warsaw, Nidzica, Modlin. This way, the German troops took the shortest route from Prussia to Warsaw. Nearby Mtawa was established so called “Mława Position” and “Rzegnowo Position”. The most convenient for the defense, was line segment from the village Turza Mała to the village of Rzęgnowo. There were taken 55 bunkers, trenches and other fortifications situated along the northern slopes of the Mława Hills and on the surrounded by swamps Mławka River valley up to the Niemyje Swamp.
In this place on the 1st of September hit the German forces with a population of 44 thousand soldiers. Defense of the “Mława position” lasted 80 hours and was not broken by the Germans. The retreat of the Polish army took place on the orders of the commander of the “Modlin”army. To this day, preserved in various conditions - 55 concrete objects. They are mostly one-and double – shooting range fortress pens to “tradyktorowy”fire machine guns and a few complexes of wood and earth fortifications. Much of the objects are currently in forest areas and is not seen as in war years. In addition to standard crossbow trenches and run-to ditches there were well preserved remains of two passive shelters.