It was a fait accompli.

Meaning

Something that has already been decided or done and cannot be changed.

Examples

• John: Is there any chance of changing the schedule?
• Alice: I'm afraid not. <b>It was a fait accompli</b> before we even started discussing it.
• John: I see. So, it's set in stone?
• Alice: Unfortunately, yes. <b>It was a fait accompli</b>, and nothing can be altered.