Gordian III, AR antoninianus, Rome. AD 238-239. 

IMP CAES M ANT GORDIANVS AVG, radiate, draped and cuirassed bust right.
PM TR P II COS PP, Mars standing left, in military dress, holding transverse spear and resting right hand on shield.

RIC IV-3 28;RSC 192.
Rated rare.

Image courtesy of the Fralin Museum of Art.