Marsic Confederation Authority in from 91 BC to 88 BC.
The Marsic Confederation was an alliance of cities opposed to Rome during the Social War (from socii ("allies") of 91-88 BC.

The conflict developed out of dissatisfaction amongst the allied Italian peoples, who served in the Roman armies but did not enjoy equal compensation in terms of political rights and compensation in booty and land. The war was begun by the Picentes.

The Confederation included Marsi, Peligni, Piceni, Vestini, Samnium, Frentani, Marrucini, and Lucani. The group intended to form an independent nation called Italia with its capital at Corfinium (modern day Abruzzo). Their coinage, modeled on the Roman denarius system, prominently depicted a female personification of Italia and oath-taking scenes reflecting the origins on the anti-Roman alliance, and other types picturing anti roman propaganda. While the alliance was defeated on the battlefield, Rome eventually ended up enfranchising all of Italy, effectively acceding to the alliance's demands.
Marsic Confederation
An AR Denarius struck 89 BC in Bovianum
Obverse: Laureate head of Italia left; VITELIV ( = ITALIA) retrograde in Oscan script behind.

Reverse: Soldier (or Mars?) standing facing, head right, left foot on lorica, holding inverted spear in right hand and sword in left; to right, recumbent bull facing, head left; I in exergue.

Diameter: 21 mm
Die Orientation: -
Weight: 3.75 g
"A new era of violence and conflict visited the Republic when in 91 B.C. Marcus Livius Drusus, a new Tribune with ideas much like the Gracchi brothers, acted as advocate for the urban and rural poor and the indigenous Italian peoples. Not only did he double the size of the senate by promoting 300 leading equites, but he tried to modify grain laws and to address old grievances over land distribution and eligibility for citizenship. Drusus' actions aroused such anger that he was murdered before his term had ended. It was the proverbial straw that broke the camel’s back, and the response among Rome’s Italian allies – who for decades had petitioned fruitlessly for improved status – was to break into revolt. The rebels comprised several Italian tribes, with the Marsi and the Samnites assuming leading roles in what came to be known as the Social War (91-87 B.C.). The capital of their breakaway state was Corfinium, where the rebels established a parallel system modeled on the institutions of the Republic, complete with a senate, consuls and praetors, and the prerogative to issue coins. After a faltering start, the Romans gained traction under the military leadership of Gaius Marius and Lucius Julius Caesar. None the less, the war was costly and destructive, and Caesar hoped hostilities would end when, in 90, he instituted the lex Iulia. The law granted full citizenship to Italian allies who were not actively engaged in making war on Rome. Though it represented progress, not every Italian insurgent was prepared to cease hostilities, and the war continued. Even with extraordinary generals such as Marius, Sulla and Gnaeus Pompey winning victories for the Republic, the war was so burdensome that leaders did not want to pursue it to the bitter end. Romans had been forced to raise more legions than at any time since the invasion of Hannibal, they struck more denarii in 90 than in any other year of the Republic, and from 89 to 87 silver was in such short supply that the purity of the denarius was reduced to slightly less than 95%. Perhaps the deciding factor, however, was a problem far from Italy: the Pontic King Mithradates VI was taking advantage of Rome’s distraction to expand his territories. In the darkest hour of the First Mithradatic War (89-85), Mithradates coordinated the murder in a single night of some 80,000 Romans in Asia Minor, and led an invasion of the province of Asia. With this tremendous concern, the Romans finally met the demands of the rebels for the complete enfranchisement of Italy – a promise that still required another eighteen years to fulfill. "

Provenance: Roma Numismatics Auction XVI (26 September 2018), lot 537. Ex Bolaffi Spa, Auction 29 (30 November 2016), lot 80.
Campana group 9b, 141 (D97/R118).
An AR Denarius struck 90 BC in Corfinium
Obverse: Laureate head of Italia left, ITALIA upwards behind.

Reverse: Oath-taking scene: Youth kneeling by standard, holding pig at which eight soldiers (four on each side) point their swords, C in exergue.

Diameter: 19 mm
Die Orientation: -
Weight: 3.64 g
Provenance: Ex Roma Numismatics, Auction XVIII (29 September 2019), lot 842; Ex Baldwin's Auctions Ltd - M&M Numismatics Ltd - Italo Vecchi Ltd, The New York Sale I (3 December 1998), lot 4; Ex 'R. J. Graham' (Paul Tinchant) Collection, J. Schulman, Auction 243 (8 June 1966), lot 1400. Published in A. Campana, La monetazione degli insorti Italici durante la guerra sociale 91-87 A.C. (Modena, 1987)
Campana 63i, D36/R54 (this coin).
An AR Denarius struck 88-87 BC in Military Mint | Campania
Obverse: Bust of Minerva left, wearing aegis and crested helmet, crowned by Victory standing behind her.

Reverse: Soldier(or Mars?), nude to waist, standing facing, helmeted head turned right, holding lance with his right hand, sword in his lowered left hand; on left, four shields attached to a tree, on right, forepart of bull reclining right, in exergue, IIIV.

Diameter: 19 mm
Die Orientation: -
Weight: 3.72 g
Provenance: Ex Othon Leonardos collection, J. Schulman, Amsterdam (31 May 1927), lot 339. Ex Joseph Martini collection, R. Ratto, Lugano (24 February 1930), lot 247. R. Ratto, Lugano - Fixed Price List VIII (1933), lot 176. Numismatica Ars Classica, Auction 70 (16 May 2013), lot 97. Numismatica Ars Classica, Auction 92 (23 May 2016), lot 1787. Hess Divo, Auction 338 (3 December 2019), lot 2.
Campana 121, 170c (this specimen, illustr. on pl. 9)