With the I Reserve Corps, he fought in the Battle of Łódź (1914) and in the Romanian campaign (1916-1917) in which he failed to achieve a decisive breakthrough after being defeated by the Romanians at Dragoslavele, 8 miles from the town of Câmpulung. Von Morgen argued that much more of the Romanian Army could have been captured if a breakthrough would have been achieved at Câmpulung. He insisted that this would have achieved "a real victory, a Cannae, a Tannenberg".