The above coin is an unusual left facing obverse portrait for Probus. Typically, Probus' left facing portraits are either Radiate and helmeted, with spear and shield or just spear, or Radiate and wearing consular robes. This coin lacks the helmet and he holds only a spear. The reverse is a common type, CONCORD(IA) MILIT(VM), Emperor clasping hands with Concordia. The type signifies unity of the military. Probably minted, in 277 AD, to commemorate Probus' restoration of peace to the Empire. Interestingly, despite the seeming unity between Emperor and his army, his troops murdered him in AD 282 because of his declaration that with the empire at peace there was no longer a need for an army. This coin was minted at Siscia, possibly Probus' city of birth. [RIC 650].
The following coin was also minted at Siscia and shows the left facing Radiate portrait, this time with spear and shield. The reverse shows Sol as the "Protector of the Emperor," CONSERVAT(OR) AVG(VSTVS). [RIC 670]. Many of Probus' coins depict the diety Sol. The cult of Sol spread rapidly during the third century, especially among the army. The army favored a particular sub-cult, Sol Invictus. Aurelian, under whom Probus served as a general, minted a variety of coins depicting Sol. He even founded a massive temple to Sol Invictus. Probus inherited many of Aurelian's types. The radiate crown, worn by Caracalla on his new coin type the Antoninianus and by all subsequent emperors on the antoninianus type, is a mundane attempt by the emperor to identify himself with Sol.
This coin shows one of the more interesting obverse types of Probus. Here Probus is facing left and wearing the Imperial Mantle, or Consular Robes and holding an eagle tipped scepter. The consular robes were the part of the symbols of Imperial power and were ornately embroidered togas made with purple threads and decorated with gold. This coin shows that the mantle was indeed ornately decorated, showing a medallion on the breast and various makings on the facing shoulder. The reverse in shows another of the Sol types minted by Probus: Sol riding in a four-horsed chariot, quadriga, facing. The inscription is SOLI INVICTO, "Sol the Invincible." Note the stones under the horses. The mintmark T/XXI, indicates that the coin was minted by the third officina, but does not indicate which mint. The coin has been attributed to the mint of Siscia. Which illustrates the danger of trying to associate letters with mints. I first assumed that the mint was Ticinium, a known mint used by Probus, but further research lead me to Siscia as the mint. [RIC 776].Any comments would be appreciated at: email@example.com