Prussian Guards

My nan is German. She told me that her father was in the German army and a member of the Prussian Guards.

I cannot find anything on the internet about them.

Does anybody know anything about them?

My nan told me that he was Crown-Prince Wilhelm's batman for a bit and also fought at the Somme. I want to know if this is true.

Undoubtedly he was probably part of the Grenadier Guards Korps. The Grenadier Guards were formed from the strongest men in the Prussian (and later German) Army, and had an outstanding record of battlefield achievements. When the Wermacht was formed, the Grenadier Guards Korp was probably composed mostly of Prussian men, as an honour to their past, and protected Germany's hierarchy.

http://web2.airmail.net/napoleon/Pru..._regiments.htm

Do you know what their uniforms look like?

I ask because we have an very old photo of him in uniform.