Count Philip Wilhelm soon took him as a cornet to his regiment, and he fought as a second lieutenant in the War of Spanish Succession. He had been promoted to first lieutenant by the time of the sieges of Kaiserswerth and Venlo. From 1702 he became general adjutant of Dubislav Gneomar von Natzmer. With Natzmer's help, Platen became a deputy in the Gensdarmes' regiment. In 1703 he was involved in the siege of Bonn. He was captured at the Battle of Höchstädt (1704), when the French army under Claude Louis Hector de Villars defeated the imperial armies; he was soon exchanged.