the advances made by the two german armies now threatened to encircle the polish modlin army from both sides, but the modlin army was forced to hold the line to stop the germans from reaching warsaw too quickly and in order to keep the retreat routes for polish units further east open – army poznan especially, which had been positioned the furthest west out of any polish army and which, although not under any major german attack, now had to scramble to fall back in line and close ranks with the retreating pomorze army and lodz army.