This is another work of the famous Dutch artist Jan Hoynck van Papendrecht who specialized in military subject. His full biography you can read here. And I have more extensive story about another watercolour by him in an earlier blog
This specific watercolour depicts a German Hussar (light cavalry) of the Brandenburger Husaren Regiment Nr. 3 – Husaren Regiment Von Zieten (Brandenburgisches) Nr. 3 and has the typical refinement of HvP.
It is dated 1901 in which period he made trip to Germany to study their uniforms and make paintings. There are several more of similar paintings from the same period that can be found here