Severina

Severina, wife of Aurelian (270-275).
Her coins as ruler of the Roman empire.

Many imperial women had coins issued in their names because they were wives or relatives of the male ruler. Only Severina had coins issued in her name because she was the Roman ruler. (Zenobia of Palmyra was a local ruler but did not lay claim to the entire empire and Eudoxia, wife of Arcadius, may have been the de facto ruler, but she did not claim to rule alone.) Coins of Severina's reign were issued during the interregnum after Aurelian was assassinated and before Tacitus was chosen to succeed him. The coin at the upper right is one of them.
22-21 mm. 3.7 grams.
SEVERINA PF AVG (including "PF")
CONCORDIA AVG   (with only one G)
Male figure on the left shaking hands with female figure on the right (Note their clothing; the man is togate).
VI in middle field low (for officina 6), and XXI in exergue.
RIC Severina 19, page 318. RIC on-line temporary 3203. "Sept. - Nov. 275"

This type for Severina as ruler is seldom offered. Furthermore, when it is offered, it may go recognized, even though it was the subject of the cover article in the March 2006 issue of The Celator. This webpage is derived from that article by John C. Christiansen.

How can it be that a woman was Roman ruler? How do we know there were coins issued for her as ruler (and, not just as wife of Aurelian)?

The story of Severina becoming ruler is told by an ancient historian (below). That she issued coins affirming that she was ruling in her own right is supported by at least three coin types:
1) The type above with "PF" and "AVG". The obverse legend includes "PF" which is isssued only for rulers ("Pius Felix" for men, but "Pia Felix" for her). Severina is the only female with "PF" in an obverse legend. The reverse legend ends "AVG" with one "G". Similar types had been issued with two Gs (next coin), so on this issue one of the rulers is gone and that one would be Aurelian, now dead. Of the two figures, the female is on the right, the superior position. The male might represent the Senate and the type concord between the Senate and Severina.
2)  CONCORDIA MILITVM, a type not issued for other women, which suggests support by the army, which is necessary for a new ruler.
3)  PROVIDEN DEOR, another type not issued for other women, which suggests support by the gods (discussed below).

On the first coin (above), the two figures shaking hands on the coin above are not Aurelian and his wife, and not Concordia (left) and Aurelian (right), because the female is on the right. When the concord is between husband and wife the female is on the left (not the right), as next, which does show concord between Severina and Aurelian.

Severina
21 mm. 3.99 grams.
SEVERINA AVG (no "PF")
RIC Severina 3, Rome.
CONCORDIA AVGG (with two Gs)
Veiled female on left shaking hands with a togate male figure (Aurelian) on the right. Note how the female is on the left.
This coin is from before Aurelian died, as the two Gs show. It is not a coin from Severina's time as ruler.
ΓXXIR
RIC 5.1, 3. Rome mint. (Page 315)

Severina as Ruler. Aurelian was a successful ruler until he was assassinated. The story (told by the ancient historian Aurelius Victor: The Caesars) goes that Aurelian was fighting against corruption and about to sack his corrupt secretary, but the secretary figured this out in time to compose letters purportedly from Aurelian indicating he was about to execute his generals. The secretary showed the letters to the generals and convinced them to take action to avoid their fate. They killed Aurelian. When they figured out they had been deceived, they killed the secretary and implored the Senate to pick the next emperor (who turned out to be Tacitus, an elderly senator). The time interval between Aurelian's death in October or November 275 and the appointment by the Senate of Tacitus is called the "interregnum" ("between reigns"). It lasted six months according to Aurelius Victor, but may really have been a much shorter period (two months?), during which Severina exercised executive power, presumably along with the Senate. Note that Aurelian reformed the coinage in 274 and all of her coins are post-reform coins, so they are late in his reign or during her own reign.

Which coin types proclaim "I am the new ruler!"? Roman imperial coin types carry messages. Surely one of the most important messages is "I am the new emperor!" (and the decision is settled, so accept me and get on with it). This message is not conveyed by stock types such as "PAX" and not by references to deeds performed in office. Looking across the entire Roman imperial series and keeping in mind the importance of force in the ancient world, the support of the military was essential and the (asserted) support of the gods useful, too.

Severina proclaimed that she was on good terms with the army, as demonstrated by her many CONCORDIAE MILITVM coins. That message is unknown for other empresses.

Severina
CONCORDIAE MILITVM
Concordia (Severina) holds two standards.
V in the field
XXI in exergue

This type is likely from her reign, but it does not have the "PF" like the top coin does.
RIC 5.1, 20. Antioch mint. (Page 318)
RIC on-line temporary 3196. "early 275 - Nov. 275"

The same message is on a similar type.

Severina
23 mm.
CONCORD MILIT, Concordia seated left
•D•L• in exergue
RIC 5.1, 1. Lugdunum mint. (Page 315, plate IX.133)
RIC on-line temporary 1348 "mid 275" (during the interregnum).

Supported by the gods. One uncommon Roman imperial type which emphasizes that the choice of ruler is correct and supported by the gods is PROVIDEN DEOR[VM].

Severina
23 mm. 4.97 grams.
PROVIDEN DEOR
"Providence of the gods"
"Foresight of the gods"
Female standing on the left holding two standards, greeted by radiate Sol on the right, raising his right hand and holding globe in left.
UXXT in exergue.
RIC 5.1 Severina 9, Ticinum mint. (page 316, plate IX.136).
RIC on-line temporary 1553. "Nov. 274 - Sept. 275"

Conclusion. Severina was ruler of the Roman empire for a few months during the interregnum after Aurelian was murdered and before Tacitus was chosen by the Senate to be the next emperor. Attributed to her reign are three types--not issued for any other empress--with the message that she is the new ruler.

References.