Field Marshal John Ligonier, 1st Earl Ligonier,, was a French Huguenot exile, born Jean Louis de Ligonier in Castres, Southern France. He had a long and distinguished career in the British army and was appointed Commander-in-chief in 1757.

Castres is the sole subprefecture of the Tarn department in the Occitanie region in Southern France. It lies in the former province of Languedoc, although not in the former region of Languedoc-Roussillon. In 2018, the commune had a population of 41,795.