There’s a lot more to the Templars, of course. They became the greatest bankers in the world, they did not cut their beards or hair (nor did they bathe, based on reports from that period). And in the end, the King of France plotted their demise by colluding with His Holiness, the Pope.
Some say that The Order of Knights of the Hospital of Saint John of Jerusalem (Knights Hospitaler) copied the black and white of the Beauceant and incorporated it into the white cross on the black field that they wore on their surcoats (also called a herigaut or gardecorps) and shields. Sometimes this order are also referred to as the Knights of Malta, in which case, the cross is referred to as the Maltese Cross. There’s a lot of complex history here and I’m not going to delve further, except to say that the Germans adopted this iconography during the First World War.