Of his experiences during the years from 1803 to 1813 little specific is known. But the fact that his biographer Van der Aa complains that he was "persecuted" by "French agents" indicates that he may still have been active as a British agent. After the Battle of Leipzig in 1813 he joined the headquarters of the Allies. After the return of the Prince of Orange to the Netherlands in 1813 van Kinckel again joined the Dutch diplomatic service. He was appointed envoy at no less than three German princely courts at the same time: the Grand Duchy of Baden, the Kingdom of Württemberg, and the Kingdom of Bavaria in 1814. These embassies he would exercise until his death in 1821.