Toynbee "Rubicone"
the Rubicon, small river of N. Italy, which falls into the Adriatic, a few miles N. of Rimini; during the period of the Roman Republic it formed the boundary between the province of Cisalpine Gaul and Italy proper. The stream is celebrated in history on account of Julius Caesar's passage across it at the head of his army in 49 B.C., by which act he declared war against the Republic.

The Emperor Justinian (in the Heaven of Mercury) mentions it in connexion with this incident in his account of the exploits of the Roman Eagle, [Par. vi. 61-62] [Aquila_1]; Caesar's crossing of it is also alluded to by Pier da Medicina (in Bolgia 9 of Circle VIII of Hell) in connexion with Curio, [Inf. xxviii. 97-98] [Curio_2]; Tityrus (i.e. D.) refers to Ravenna as being situated on the coast of Emilia, between the right bank of the Po and the left bank of the Rubicon, Egl. iv. 67-68 [Po: Ravenna].

The identification of the classical Rubicon has been the subject of a long dispute between the various towns and villages in the district N. of Rimini, the question being eventually (in 1756) referred to Rome for decision, when judgement was given in favour of the claim of the Uso, which enters the Adriatic a short distance N. of Savignano. The most recent investigations tend to show that the Rubicon has entirely quitted its ancient course, and it is now identified with the Fiumicino, into which it appears originally to have fallen, while at the present day its upper part, known as the Urgone, unites with the Pisciatello.

©Oxford University Press 1968. From A Dictionary of Proper Names and Notable Matters in the Works of Dante by Paget Toynbee (1968) by permission of Oxford University Press