Lieutenant-Colonel Frederick von der Decken, [K.H.], entered the service of the newly raised King's German Legion in 1804, was commissioned Lieutenant in February 1806, and promoted to Captain on 18.11.1811. He served in the Expedition to Hanover in 1805, in the Baltic in 1807, the Peninsula between 1809-13, the South of France between 1813-14, the Netherlands in 1814 and at Waterloo in 1815. During this time he was slightly wounded in the knee at Salamanca on 22.7.1812, where, apparently, he was carried onwards by his charger until he fell unconscious to the ground. He appears on the Half-Pay of the British Army from 24.2.1816, then is listed as Lieutenant-Colonel by Brevet, 1st Hanoverian Dragoons. He was created a Knight of the Hanoverian Guelphic Order and was a recipient of the Hanoverian King William's Cross.