@Stevearino coin came up at a recent @John Anthony auction, I found it intriguing. Constantine I, AD 307-337. Roman billon follis, 6.38 g, 25.3 mm, 1 h. Trier, Autumn 307-end 308. Obv: IMP CONSTANTINVS P F AVG, laureate, draped and cuirassed bust, right, seen from rear. Rev: MARTI PATRI CONSERVATORI, Mars standing right, holding inverted spear and resting hand on grounded shield, S|A//PTR. Refs: RIC vi, p. 217, 774; Cohen 359; RCV 16002. MARTI PATRI CONSERVATORI is a title not previously used on Roman coins. Here, Constantine is likened to Mars because of his defeat of the Franci and Alemanni.* This reverse type was primarily used in Trier and Lugdunum, and it antedates Constantine's assumption from Caesar to Augustus. This coin (Triskeles sale 22, lot 530, 15 Dec 2017), was issued for Constantine I as Caesar. Note it has a laureate and cuirassed bust type, seen from the front. The coin then appears with the same bust type after Constantine's promotion to Augustus (Naumann Auction 9, lot 772, 3 Nov 2013). Mine has a different bust type -- perhaps used subsequently -- depicting Constantine laureate, draped and cuirassed and seen from the rear. Mine's a bit worn to fully appreciate this, but it is better seen on this example from CNG. Post anything you feel is relevant! ~~~ *Stevenson, Seth William, et al. A Dictionary of Roman Coins, Republican and Imperial. G. Bell and Sons, 1889, p. 540.