While wearing the uniform is customary, since the prince was in the military until 2015, the problem was he was not clean-shaven.
According to Daily Mail, it’s a breach of military rules to wear a beard “while on official duty in a British Army uniform.” A currently serving member of the cavalry regiment was disappointed in the prince.
The member said, “Prince Harry is letting us all down. There’s no place for beards in the Queen’s cavalry. He should have shaved it off for such an important day.”
There are a few rare circumstances in which the British Army rules allow beards, like when a soldier is suffering from a skin condition or has strong religious reasons for not cutting their hair.
Special Forces or other service members on covert operations are allowed to have beards while behind enemy lines, and the Royal Navy allows the style as long as it’s full enough.
A select few Pioneer Sergeants have worn beards when on official duty, but the Queen’s personal guard has never been afforded the same privilege.
But since Harry is no longer serving, he isn’t bound by the same regulations. So if he wants to wear facial hair, he has every right. And of course Twitter had to chime in, with many expressing support for the royal.