跨过卢比孔河 Cross the Rubicon

解释：

To take an irrevocable step; to cross the point of no return; to commit one to a given course of action

采取不可逆转的行动；破釜沉舟；果断行事

起源：

Rubicon was a small stream that flowed into the Adriatic and in Roman times marked the boundary between Cisalpine Gaul and ancient Italy. 

在古罗马时期，卢比孔河是一条流入亚得里亚海的小河，也是高卢与古意大利的界河。

Pompey, Julius Caesar’s political enemy, feared that Caesar was getting too powerful and influential. He conspired with the Senate to dismiss Caesar from his post and forbade him to cross the Rubicon.

庞培是裘利斯·凯撒的政敌，他担心凯撒的权势和影响越来越强。于是，庞培与元老院密谋撤销凯撒的职务，并禁止他跨过卢比孔河。In 49 B.C., after some hesitation, Julius Caesar crossed the Rubicon to march against Pompey in defiance of the Senate’s orders.

在经过一段时间的犹豫后，凯撒在公元前49年，违反元老院的命令，率大军渡过卢比孔河。

Those were reported that he ordered his army to burn all the ships and exclaimed, “The die is cast,” thus committing himself to conquer or to perish. This act boosted the moral of his men enormously. And finally his troops crushed Pompey’s army and took over Rome. Julius Caesar was given a mandate by the people to rule as dictator for life.

据说，他在大军渡河后，下令烧掉所有的战船，说：“骰子已经掷出去了。”以示背水一战的必胜信心。此举使其军队的士气大振，终于夺取了罗马。裘利斯·凯撒随后被人民拥戴为终生独裁者。

例句：

Once the matter is taken up to the court, both the employer and the employees have crossed the Rubicon. It is hard to predict how things are going to turn out.

这事一旦交到法庭手里，那劳资双方都没有后退的余地。很难说最后会有什么结果。