Gallienus, AE antoninianus. Rome. Sole reign. AD 263. 

GALLIENVS AVG, radiate head right.
MARTI PACIFERO, Mars standing left, holding olive branch,
spear and shield. 
No mintmark.

RIC V-1 Rome 236; Goebl 0569a; Sear 10288.

Image from the Dalheim hoard catalog.