As the Germans opened what would become the battle of Tannenberg, Lt. Gen. Otto von Below of I Reserve Corps ordered his 36th Reserve Division to unhinge the left flank of the Russian VI Corps, anchored on the southern shore of the Bössauer See. To help take this strong position, he attached the 6th Landwehr Brigade from the garrison of Fort Boyen, telling the division staff to use them as "auxiliary strength" - in modern jargon, a "force multiplier."

Below advocated a complicated attack plan and the division staff concurred. The Landwehr and reservists carried it out pretty much as planned, striking the Russians from three different directions. The Russian pulled back from their strong position on the south end of the lake, forcing the entire corps to pull back with its flank now exposed. That in turn opened the right flank of the Russian XIII Corps to the southwest, causing it to pull its own troops back to refuse its flank and opening a large gap in the Russian lines that would lead directly to the massive defeat of Tannenberg.