First World War
Prince Leopold's retirement, however, did not last long. On 16 April 1915, he was given command of the German 9th Army, replacing General August von Mackensen. Leopold quickly proved himself an able commander as he took Warsaw on 4 August 1915. Following this success, he was put in command of Army Group Prince Leopold of Bavaria (Heeresgruppe Prinz Leopold von Bayern), which was a German force in the central/northern sector of the Eastern Front. He was awarded the Grand Cross of the Military Order of Max Joseph on 5 August 1915, the prestigious Pour le Mérite, Prussia's highest military decoration, on 9 August 1915 and the oak leaves to the Pour le Mérite on 25 July 1917.
On 29 August 1916, after the brutal summer campaigns succeeded in reversing the Brusilov Offensive against the Austrians, Leopold became the Supreme Commander of the German forces on the Eastern front (Oberbefehlshaber Ost), succeeding Field Marshal Paul von Hindenburg. Leopold held this post for the rest of the war. Because of his position, Leopold was a potential German candidate for the throne of the puppet Kingdom of Poland.
On 4 March 1918, Leopold received yet another high honor, the Grand Cross of the Iron Cross, awarded only five times during World War I.
Prince Leopold retired again in 1918 after the signing of the Treaty of Brest-Litovsk, which had ended the war on the Eastern Front. This treaty was highly favorable to Germany, and Leopold ended his career with success. He died on 28 September 1930 in Munich and is buried in the Colombarium in the Michaelskirche in Munich.
