From early September 1914 to mid-March 1915, General Ruzsky was the commander-in-chief of the entire Northwestern Front. Under his command, the forces of the front fought at the Vistula River and Łódź, but despite huge success of the 1st and 10th Armies, he was ordered to retreat, due to a group of German troops commanded by General Reinhard von Scheffer-Boyadel was able to snuck out from the encircling movement. He and his troops also participated in the disastrous battle at the Masurian Lakes. In the latter, General Ruzsky was the one who caused the catastrophe of the 10th Army.