the die is cast
a decision is made that cannot be changed

[TahlilGaran] Dictionary of Contemporary English ▲

die is cast
a decision is made that cannot be changed.
When the first shot was fired, the die was cast and a revolution began.

Etymology: based on the idea that after you cast (= throw) a die (= small square block with a number on each side) you cannot control its movement

[TahlilGaran] English Idioms Dictionary ▲

die is cast
a decision has already been made and you cannot change it
We have decided to move to Paris. Now the die is cast and we cannot change our plans.

[TahlilGaran] English Idioms Dictionary ▲

die is cast
v. phr., literary To make an irrevocable decision. (From Julius Caesar's famous words in Latin, "alea iacta est", when he crossed the river Rubicon, which meant war.)
Everything was ready for the invasion of Europe, the die had been cast, and there was no turning back now.

[TahlilGaran] English Idioms Dictionary ▲