Formerly a member of the Royal Guards in the ancient years of Equestria. Greatshield once dutifully carried out his service to guard the Princess and defend Equestria in times of conflict. He always strived to join the most decorated high ranking members of the guard, however during one battle his fate would be change forever.
 
He mysteriously disappeared in the battlefield and was thought to have been killed in battle and given up for dead. Last seen falling of a cliff and into the ocean. The reality was that he fell through a dimensional rift and emerged on the other side in the human world in the early 1920’s. In the human world, he tried several time to find a way back to Equestria while at the same time experiencing both the glamour and glitz of the roaring 20’s (experiencing his first drink of alcohol) and suffering and pain of the Great Depression in the 1930’s. Having eventually given up on trying to find a way back and accepting his fate, he set out to find his place in this new world. Taking on the guise of a private investigator in 1928 and had taken up residence in a small flat near downtown. The very same flat that would be occupied by Sunset Shimmer decades into the future. These days, he’s known as Detective Greatshield.
 
His old Helmet is on Display in his office and from time to time he would reminisce about his old life in Equestria, much to the confusion of his clients, who would sometimes be present during these times of remembering.