The official Anthem of the Abbey-Principality of San Luigi is “Partant pour la Syrie”, composed around 1807 by Hortense de Beauharnais and Alexandre de Laborde.

>>Partant pour la Syrie at Wikipedia

In addition, a March Song was composed for the Order of the Crown of Thorns by Chevalier Frederick Bowman, KCT, in the 1960s, the first page of which is reproduced below.