Throughout his life Bülow was devoted to music, his great musical ability bringing him to the notice of King Frederick William II of Prussia, and c. 1790 he was conspicuous in the most fashionable circles of Berlin. He did not, however, neglect his military studies, and in 1792 he was made military instructor to the young Prince Louis Ferdinand of Prussia, becoming at the same time full captain. He took part in the campaigns of 1792-94 on the Rhine, and received for signal courage during the siege of Mainz the order Pour le Mérite and promotion to the rank of major.