Caubeen - headdress of the Irish Fusiliers of Canada. It is navy blue with green shamrock . The caubeen is an Irish beret formerly worn by peasants. The name caubeen dates from late 18th century Irish, and literally means "old hat". It has been adopted as the head dress of Irish regiments of Commonwealth armies. In the British and Canadian armies, the caubeen is officially known as the "bonnet, Irish, green".