The Rubicon is a river of Central Italy, falling into the Adriatic a little north of Ariminum, that has obtained a proverbial celebrity from the well-known story of its passage by Julius Caesar, in the middle of January, 49 BC. It formed the southern boundary of his province, so that by crossing it he virtually declared war against the Republic. Caesar himself makes no mention of its passage; Suetonius, Plutarch, and Lucan tell how he hesitated awhile on the bank and then crossed with the words, Jacta est alea ("The die is cast").