 Complete the following phrase:  During the First World War, Manstein served on both the German Western and Eastern Fronts. At the beginning of the war, he was promoted to lieutet and participated in the invasion of Belgium with the 2nd Guard Reserve Infantry Regiment. In August 1914, he took part in the capture of Namur, the site of a massive citadel surrounded by outlying forts. In September, Mansteins unit was one of two transferred to East Prussia and attached to the Eighth Army, commanded by Hindenburg. After seeing action in the 