The 1st Foot Guards was an infantry regiment of the Royal Prussian Army formed in 1806. The regiment considered itself the most noble regiment of Christendom (vornehmstes Regiment der Christenheit). The regiment was disbanded in 1919, with the Infantry Regiment 9 Potsdam

Infantry Regiment 9 Potsdam

Infantry Regiment 9 of Potsdam was an infantry regiment in Weimar Republic's Reichswehr and Nazi Germany's Wehrmacht, descended from famed 1st Prussian Regiment of Foot Guards in German Empire's Deutsches Reichsheer....

 of the new Reichsheer bearing its tradition. The Wachbataillon

Wachbataillon

The Wachbataillon is the German Bundeswehr's elite drill unit. The Wachbataillon is the largest battalion of the German forces with about 1,800 soldiers, split in two garrisons in Berlin and Siegburg...

 of the Bundeswehr

Bundeswehr

The Bundeswehr consists of the unified armed forces of Germany and their civil administration and procurement authorities...

considers itself in the line of this regiment.

All Princes of Prussia were appointed lieutenants in the 1st Foot Guards upon their tenth birthdays.
Chief of the regiment was always the King of Prussia.