He was given command over the Fifth Army which he led in the Battle of Galicia and the defence of Lodz. The following year he switched command to the new Twelfth Army, which he led in the Second Battle of the Masurian Lakes in February 1915 (where the Russian Tenth Army was defeated by the Germans). He subsequently returned to command of Fifth Army and, briefly, commanded the northern sector of the Eastern Front. Plagued for years by poor health Plehwe was finally invalided out of the army in February 1916; he died later the same year.