I’d like to follow up on a suggestion raised by @maridvnvm in another post ( https://www.cointalk.com/threads/mars-vs-sol-in-the-first-tetrarchy.353123/page-2#post-3992120 ). I’m curious about the origins of Constantine’s Sol coinage and whether we can determine which mint was first to strike it. Most know that Sol had long been a deity featured on Roman coinage. A standing or advancing Sol appears on coins of Septimius Severus, Elagabalus, Valerian, Postumus, and Aurelian, among several others. A scarce antoninianus struck at Lyon in 293 A.D. for Constantine’s father (RIC VI Part 2 Lugdunum 631c) depicts Sol standing left, holding a whip and raising his right hand. Sol was nothing new. But Sol was not featured on the early coinage of Constantine; Mars and the Genius of the Roman People were. Yet in about 310, Sol coinage for Constantine explodes. Lyon, London, and Trier were the earliest to strike Sol coinage. Mints of Ticinum, Aquileia, Rome, and Ostia would begin in 312. When the mint at Arles opened in 313, it struck Sol coinage right away. Siscia would follow in 317, but it was the only Eastern mint to do so. Constantine’s Sol coinage seems to have been a Western phenomenon. The earliest date I have found for the Sol coinage is possibly 309 at Lyon, but I’m not quite sure how to read RIC here. In RIC VI, p. 240, Sutherland writes: The operative issue here concerns the phrase “continuation of the issue into 310.” I take that to mean that Sutherland believes that Constantine’s Sol coinage was not struck until 310. Maridvnvm seems to concur, suggesting that the mint at Lyon experimented with iconographical designs before settling on the standard "Sol standing with raised hand and globe" type. Such experimentation might suggest Lyon as the starting point for the Sol coinage. But Maridvnvm still posits a 310 starting date. These are two early Lyonese Sol issues he posted (his coins), and his commentary: I do not own Bastien, so I don’t know what he says about dating. Why does this 309/310 distinction matter? Well, for two reasons: 1. Some indifferent attributions will just give the general issue date of 309-310 (Example: https://www.vcoins.com/en/stores/gb...n_mint__ricvi_312__scarce/878967/Default.aspx ). Obviously, if Sutherland did not intend for the 309 date to apply to Sol coinage from that issue, such an attribution would be incorrect. (In fairness, the "ca." abbreviation before a date might merit some grace here.) 2. More substantively, Sutherland and others have argued that the explosion of Sol coinage was the result of Constantine’s vision of Apollo / Sol in 310 (a vision that Peter Weiss claims gets a later Christian re-interpretation as the “cross in the sky” vision recounted by Eusebius). This causal connection (the Sol vision leading to Sol coinage) is weakened if Lyon starts striking Sol coinage for Constantine in 309, before the vision. If you’re still reading this post, what’s wrong with you? I suppose what I most want to know is whether a 309 date for the Lyonese Sol coinage is feasible, or if the 310 date is the only plausible beginning date. I vote for the latter.