He was a staunch Jacobite and in 1745 accompanied Charles Edward Stuart (then known in Jacobite circles as the Prince Regent, or Bonnie Prince Charlie) to Scotland, serving as "aide-de-camp" at the battle of Falkirk (January 1746). Escaping to France, he served with Marshal Saxe in the Low Countries, and at the capture of Maastricht (1748) was made a "maréchal de camp".